From nobody Mon Apr 6 15:26:03 2026 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 13F69369225; Fri, 3 Apr 2026 19:06:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775243180; cv=none; b=PT84DJt2kDQg2Rw+uZqWfLST+PVkgVh5DGIZY2p7ZPfhzqBg6Cs+x/hrnoC4UbUoDDmHPkjeHesPN2mZh33hDOdyJs9ngYJzuSu1OzpA0764SqgYsJkcv2tmP+w5/IWIEm8rpfaxDKxafXfsmlatE3FzKnglpDzI4b9K8Wa5XEI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775243180; c=relaxed/simple; bh=kQx2w6tjXS70FM6QN8ZD2XsXn3DcBvyYIGxSEVKnzeg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VNJRtOfuBwv3zInZg6F3nNofewdckRkYZ4notiZIyzcKLciqdT/2yKCWAAgpRhh5Yw6XDr4a+/0145WxqFMiVgN9EC7E4SyyHrQ/wlio+jRq8rQsH5juqcSy1tzwKZ+SKxvCIfcFl1rmt5YqUI6hTgBgIJCmvKp6lYfn1gkDwRg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=LZVrFFPo; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="LZVrFFPo" Received: by linux.microsoft.com (Postfix, from userid 1241) id CD7ED20B6F08; Fri, 3 Apr 2026 12:06:18 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com CD7ED20B6F08 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1775243178; bh=/2DAmCjc8SwftdIXiNdKNR+rhLn04r/3WgiKSyZp/C8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LZVrFFPoH2ZOMAfozYttxNb43tMnOShX418hsfi2bG8mpphlgaHaFh2HkyUnFs45/ 73G2v5UmNX0qoVoSFvBBodXuWFgAu4L6zfgC5C3fSSHuSUnN7A5u+uzgcqZ9Q3uHNS V9FVProCEZzsGcj43Z4FEeoMR4R2FX1PsbsirDZw= From: Jork Loeser To: linux-hyperv@vger.kernel.org Cc: x86@kernel.org, "K . Y . Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Arnd Bergmann , Michael Kelley , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Jork Loeser Subject: [PATCH v2 1/6] Drivers: hv: vmbus: fix hyperv_cpuhp_online variable shadowing Date: Fri, 3 Apr 2026 12:06:07 -0700 Message-ID: <20260403190613.47026-2-jloeser@linux.microsoft.com> X-Mailer: git-send-email 2.43.7 In-Reply-To: <20260403190613.47026-1-jloeser@linux.microsoft.com> References: <20260403190613.47026-1-jloeser@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" vmbus_alloc_synic_and_connect() declares a local 'int hyperv_cpuhp_online' that shadows the file-scope global of the same name. The cpuhp state returned by cpuhp_setup_state() is stored in the local, leaving the global at 0 (CPUHP_OFFLINE). When hv_kexec_handler() or hv_machine_shutdown() later call cpuhp_remove_state(hyperv_cpuhp_online) they pass 0, which hits the BUG_ON in __cpuhp_remove_state_cpuslocked(). Remove the local declaration so the cpuhp state is stored in the file-scope global where hv_kexec_handler() and hv_machine_shutdown() expect it. Fixes: 2647c96649ba ("Drivers: hv: Support establishing the confidential VM= Bus connection") Signed-off-by: Jork Loeser --- drivers/hv/vmbus_drv.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index 3e7a52918ce0..301273d61892 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -1430,7 +1430,6 @@ static int vmbus_alloc_synic_and_connect(void) { int ret, cpu; struct work_struct __percpu *works; - int hyperv_cpuhp_online; =20 ret =3D hv_synic_alloc(); if (ret < 0) --=20 2.43.0 From nobody Mon Apr 6 15:26:03 2026 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4C5553D4102; Fri, 3 Apr 2026 19:06:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775243181; cv=none; b=J9pFqGu66+A60vNT4mSWOk1oIEIBNxFC+rSBC3MeGtkCu8XvGXOiX5IPWlFkTvRsAS6XPZigmBx37RCBgxgtlYgSOuqGFHauBjoGskXcbOAaeqhRYth8Sz6ayLvKHYIt0O7HA/UCQkRM8TW+cgbla2i5iJ4zxHARmh20vV7ia3o= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775243181; c=relaxed/simple; bh=TGgnAFzlIDIivrxTgxPOdYRWjFMaQLSOV3k1ZpfrgAc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YaBX9AUedhVWKmq97Gl6frFqnjbPg0SvOvezad+GGOzz9dmhKAg6oP7ifqU6ApsXU+pEyLAhY0/Vy0tQEwNRPNel62WPw6KYkfyxV32VTD90VtSMvtPj7Tuviefu7NgrjdSCrxP9SaXv2hrbMjVHyEuXuA72JeuYu16aZo0KXR0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=ooPUfoBf; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="ooPUfoBf" Received: by linux.microsoft.com (Postfix, from userid 1241) id 25DD620B6F0C; Fri, 3 Apr 2026 12:06:20 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 25DD620B6F0C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1775243180; bh=oe8/Pqe4w3M//1TBoCPONOMHSy0PBbB0t+C6t5dQLKM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ooPUfoBf8oQCRKP9t9HHfupwRCMUHvaOL7HtM4MgrGi3ramxYKPMQk/iQM7Feb3rv goeUxYijM+NqXzK3XAafEJyH1DHh3SY1ty23/FKKz8KLSPpEC25iUUbAZQHPNWvuCH iQ5h9Y8hBRLZtmeJDXcafzAhxay2FOBsKi7nha40= From: Jork Loeser To: linux-hyperv@vger.kernel.org Cc: x86@kernel.org, "K . Y . Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Arnd Bergmann , Michael Kelley , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Jork Loeser , Anirudh Rayabharam Subject: [PATCH v2 2/6] x86/hyperv: move stimer cleanup to hv_machine_shutdown() Date: Fri, 3 Apr 2026 12:06:08 -0700 Message-ID: <20260403190613.47026-3-jloeser@linux.microsoft.com> X-Mailer: git-send-email 2.43.7 In-Reply-To: <20260403190613.47026-1-jloeser@linux.microsoft.com> References: <20260403190613.47026-1-jloeser@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Move hv_stimer_global_cleanup() from vmbus's hv_kexec_handler() to hv_machine_shutdown() in the platform code. This ensures stimer cleanup happens before the vmbus unload, which is required for root partition kexec to work correctly. Co-developed-by: Anirudh Rayabharam Signed-off-by: Anirudh Rayabharam Signed-off-by: Jork Loeser --- arch/x86/kernel/cpu/mshyperv.c | 8 ++++++-- drivers/hv/vmbus_drv.c | 1 - 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index 89a2eb8a0722..235087456bdf 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -235,8 +235,12 @@ void hv_remove_crash_handler(void) #ifdef CONFIG_KEXEC_CORE static void hv_machine_shutdown(void) { - if (kexec_in_progress && hv_kexec_handler) - hv_kexec_handler(); + if (kexec_in_progress) { + hv_stimer_global_cleanup(); + + if (hv_kexec_handler) + hv_kexec_handler(); + } =20 /* * Call hv_cpu_die() on all the CPUs, otherwise later the hypervisor diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index 301273d61892..5d1449f8c6ea 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -2892,7 +2892,6 @@ static struct platform_driver vmbus_platform_driver = =3D { =20 static void hv_kexec_handler(void) { - hv_stimer_global_cleanup(); vmbus_initiate_unload(false); /* Make sure conn_state is set as hv_synic_cleanup checks for it */ mb(); --=20 2.43.0 From nobody Mon Apr 6 15:26:03 2026 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 48B223D5640; Fri, 3 Apr 2026 19:06:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775243182; cv=none; b=agNj9jEqZtQyAY+NYtpIOkormoX/BjxJCOI13+uAqjUrL6mD5eGteoLWAE+1ln0rGcfr018/o6chxrnskpi2x5PS/cJanJmnFxpQlmF2t/6dXL2Qevb6aAa37IIPGhsmSW2dIPuKSEs74NXUopFEACQal9VW/azpShX3mRwVBtU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775243182; c=relaxed/simple; bh=hNIiNuDPxuZnaMtc1ARblwqwK4xYSWqQw5KM4tx3lJs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nLRg+ADKEG9s4NA9fhhvvgBIi580iDl5QH4XWKmQMMfWfcF/QxDAvkwoqF2dIyfLTsbCxBRjODubjKr2v9RE3iDwB7ELy1kJPm+GEQ61EzdltZclg+MIKdTkimo+zYUzKYKkpPlGibSsslQlpFm4cExXtO5O/gMjq9dzR30QbN8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=Bg2PvURR; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="Bg2PvURR" Received: by linux.microsoft.com (Postfix, from userid 1241) id 2141F20B6F15; Fri, 3 Apr 2026 12:06:21 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 2141F20B6F15 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1775243181; bh=6pzpu/gJFjinb2P2J9+XytwM6zcdOj6YIrKwdbxm5Zs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Bg2PvURRiJE3pPwhcLClMXyqRhkiSHWEps/NqQcxncpw213FqrQy6iaXhp9pk+eMA N6DGnQeQAlm59wLPKYLmNAI8wG1I7M6Uc67ZUxMz/Ho+MlZUnYlu9ABz6koywBzQxP yOb+oWEqfoig4RznbXnpq0jgNKX2Zsns9HUWvFtk= From: Jork Loeser To: linux-hyperv@vger.kernel.org Cc: x86@kernel.org, "K . Y . Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Arnd Bergmann , Michael Kelley , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Jork Loeser , Anirudh Rayabharam , Stanislav Kinsburskii , Mukesh Rathor Subject: [PATCH v2 3/6] x86/hyperv: Skip LP/VP creation on kexec Date: Fri, 3 Apr 2026 12:06:09 -0700 Message-ID: <20260403190613.47026-4-jloeser@linux.microsoft.com> X-Mailer: git-send-email 2.43.7 In-Reply-To: <20260403190613.47026-1-jloeser@linux.microsoft.com> References: <20260403190613.47026-1-jloeser@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" After a kexec the logical processors and virtual processors already exist in the hypervisor because they were created by the previous kernel. Attempting to add them again causes either a BUG_ON or corrupted VP state leading to MCEs in the new kernel. Add hv_lp_exists() to probe whether an LP is already present by calling HVCALL_GET_LOGICAL_PROCESSOR_RUN_TIME. When it succeeds the LP exists and we skip the add-LP and create-VP loops entirely. Also add hv_call_notify_all_processors_started() which informs the hypervisor that all processors are online. This is required after adding LPs (fresh boot) and is a no-op on kexec since we skip that path. Co-developed-by: Anirudh Rayabharam Signed-off-by: Anirudh Rayabharam Co-developed-by: Stanislav Kinsburskii Signed-off-by: Stanislav Kinsburskii Co-developed-by: Mukesh Rathor Signed-off-by: Mukesh Rathor Signed-off-by: Jork Loeser --- arch/x86/kernel/cpu/mshyperv.c | 7 +++++ drivers/hv/hv_proc.c | 47 ++++++++++++++++++++++++++++++++++ include/asm-generic/mshyperv.h | 10 ++++++++ include/hyperv/hvgdk_mini.h | 1 + include/hyperv/hvhdk_mini.h | 12 +++++++++ 5 files changed, 77 insertions(+) diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index 235087456bdf..f653feea880b 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -429,6 +429,10 @@ static void __init hv_smp_prepare_cpus(unsigned int ma= x_cpus) } =20 #ifdef CONFIG_X86_64 + /* If AP LPs exist, we are in a kexec'd kernel and VPs already exist */ + if (num_present_cpus() =3D=3D 1 || hv_lp_exists(1)) + return; + for_each_present_cpu(i) { if (i =3D=3D 0) continue; @@ -436,6 +440,9 @@ static void __init hv_smp_prepare_cpus(unsigned int max= _cpus) BUG_ON(ret); } =20 + ret =3D hv_call_notify_all_processors_started(); + WARN_ON(ret); + for_each_present_cpu(i) { if (i =3D=3D 0) continue; diff --git a/drivers/hv/hv_proc.c b/drivers/hv/hv_proc.c index 5f4fd9c3231c..63a48e5a02c5 100644 --- a/drivers/hv/hv_proc.c +++ b/drivers/hv/hv_proc.c @@ -239,3 +239,50 @@ int hv_call_create_vp(int node, u64 partition_id, u32 = vp_index, u32 flags) return ret; } EXPORT_SYMBOL_GPL(hv_call_create_vp); + +int hv_call_notify_all_processors_started(void) +{ + struct hv_input_notify_partition_event *input; + u64 status; + unsigned long irq_flags; + int ret =3D 0; + + local_irq_save(irq_flags); + input =3D *this_cpu_ptr(hyperv_pcpu_input_arg); + memset(input, 0, sizeof(*input)); + input->event =3D HV_PARTITION_ALL_LOGICAL_PROCESSORS_STARTED; + status =3D hv_do_hypercall(HVCALL_NOTIFY_PARTITION_EVENT, + input, NULL); + local_irq_restore(irq_flags); + + if (!hv_result_success(status)) { + hv_status_err(status, "\n"); + ret =3D hv_result_to_errno(status); + } + return ret; +} + +bool hv_lp_exists(u32 lp_index) +{ + struct hv_input_get_logical_processor_run_time *input; + struct hv_output_get_logical_processor_run_time *output; + unsigned long flags; + u64 status; + + local_irq_save(flags); + input =3D *this_cpu_ptr(hyperv_pcpu_input_arg); + output =3D *this_cpu_ptr(hyperv_pcpu_output_arg); + + input->lp_index =3D lp_index; + status =3D hv_do_hypercall(HVCALL_GET_LOGICAL_PROCESSOR_RUN_TIME, + input, output); + local_irq_restore(flags); + + if (!hv_result_success(status) && + hv_result(status) !=3D HV_STATUS_INVALID_LP_INDEX) { + hv_status_err(status, "\n"); + BUG(); + } + + return hv_result_success(status); +} diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h index d37b68238c97..bf601d67cecb 100644 --- a/include/asm-generic/mshyperv.h +++ b/include/asm-generic/mshyperv.h @@ -347,6 +347,8 @@ bool hv_result_needs_memory(u64 status); int hv_deposit_memory_node(int node, u64 partition_id, u64 status); int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages); int hv_call_add_logical_proc(int node, u32 lp_index, u32 acpi_id); +int hv_call_notify_all_processors_started(void); +bool hv_lp_exists(u32 lp_index); int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u32 flags); =20 #else /* CONFIG_MSHV_ROOT */ @@ -366,6 +368,14 @@ static inline int hv_call_add_logical_proc(int node, u= 32 lp_index, u32 acpi_id) { return -EOPNOTSUPP; } +static inline int hv_call_notify_all_processors_started(void) +{ + return -EOPNOTSUPP; +} +static inline bool hv_lp_exists(u32 lp_index) +{ + return false; +} static inline int hv_call_create_vp(int node, u64 partition_id, u32 vp_ind= ex, u32 flags) { return -EOPNOTSUPP; diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h index 056ef7b6b360..f2598e186550 100644 --- a/include/hyperv/hvgdk_mini.h +++ b/include/hyperv/hvgdk_mini.h @@ -435,6 +435,7 @@ union hv_vp_assist_msr_contents { /* HV_REGISTER_VP_AS= SIST_PAGE */ /* HV_CALL_CODE */ #define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE 0x0002 #define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST 0x0003 +#define HVCALL_GET_LOGICAL_PROCESSOR_RUN_TIME 0x0004 #define HVCALL_NOTIFY_LONG_SPIN_WAIT 0x0008 #define HVCALL_SEND_IPI 0x000b #define HVCALL_ENABLE_VP_VTL 0x000f diff --git a/include/hyperv/hvhdk_mini.h b/include/hyperv/hvhdk_mini.h index 091c03e26046..b4cb2fa26e9b 100644 --- a/include/hyperv/hvhdk_mini.h +++ b/include/hyperv/hvhdk_mini.h @@ -362,6 +362,7 @@ union hv_partition_event_input { =20 enum hv_partition_event { HV_PARTITION_EVENT_ROOT_CRASHDUMP =3D 2, + HV_PARTITION_ALL_LOGICAL_PROCESSORS_STARTED =3D 4, }; =20 struct hv_input_notify_partition_event { @@ -369,6 +370,17 @@ struct hv_input_notify_partition_event { union hv_partition_event_input input; } __packed; =20 +struct hv_input_get_logical_processor_run_time { + u32 lp_index; +} __packed; + +struct hv_output_get_logical_processor_run_time { + u64 global_time; + u64 local_run_time; + u64 rsvdz0; + u64 hypervisor_time; +} __packed; + struct hv_lp_startup_status { u64 hv_status; u64 substatus1; --=20 2.43.0 From nobody Mon Apr 6 15:26:03 2026 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 2D8133D6462; Fri, 3 Apr 2026 19:06:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775243183; cv=none; b=Uo6+nBvQ8TyhWUM4ZEg/4J1Znw/lAAO1I0zFd0xoPyUqZrvYChU7DqcSlXZVxTowkr5ZaSn2aOPwsMqTk3X4Qmmsa4zru1B0eL6+8uEmG4fRDxqx+iAboTIHL4dKkMvO6U+uxlFptg79EYba2znwnwNtXtLY8225GdVcPX5oe+M= ARC-Message-Signature: i=1; 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Fri, 3 Apr 2026 12:06:22 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 19C8620B6F12 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1775243182; bh=yqFbFJGBvO2l2W0KOvWaYMkuE+H+5I+GiqdFgpfqbAU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=p7RDFkDZweITDckBDvOyHXRQevpVPY1inBDLq1l9IloDnUcZHbwf+9cwtIoIrmV3Z snwhxlagkdCdDuNodhFLpfe+FD7kTpR9IzmkkJNn34jhA9u7wpFN1qmZ3DCVJBe9WI HBlTX33PsVFnbaz+bYM7z7++3yhkOsGMlslTSae4= From: Jork Loeser To: linux-hyperv@vger.kernel.org Cc: x86@kernel.org, "K . Y . Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Arnd Bergmann , Michael Kelley , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Jork Loeser Subject: [PATCH v2 4/6] mshv: limit SynIC management to MSHV-owned resources Date: Fri, 3 Apr 2026 12:06:10 -0700 Message-ID: <20260403190613.47026-5-jloeser@linux.microsoft.com> X-Mailer: git-send-email 2.43.7 In-Reply-To: <20260403190613.47026-1-jloeser@linux.microsoft.com> References: <20260403190613.47026-1-jloeser@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The SynIC is shared between VMBus and MSHV. VMBus owns the message page (SIMP), event flags page (SIEFP), global enable (SCONTROL), and SINT2. MSHV adds SINT0, SINT5, and the event ring page (SIRBP). Currently mshv_synic_init() redundantly enables SIMP, SIEFP, and SCONTROL that VMBus already configured, and mshv_synic_cleanup() disables all of them. This is wrong because MSHV can be torn down while VMBus is still active. In particular, a kexec reboot notifier tears down MSHV first. Disabling SCONTROL, SIMP, and SIEFP out from under VMBus causes its later cleanup to write SynIC MSRs while SynIC is disabled, which the hypervisor does not tolerate. Restrict MSHV to managing only the resources it owns: - SINT0, SINT5: mask on cleanup, unmask on init - SIRBP: enable/disable as before - SIMP, SIEFP, SCONTROL: leave to VMBus when it is active (L1VH and nested root partition); on a non-nested root partition VMBus doesn't run, so MSHV must enable/disable them Signed-off-by: Jork Loeser --- drivers/hv/mshv_synic.c | 142 ++++++++++++++++++++++++++-------------- 1 file changed, 94 insertions(+), 48 deletions(-) diff --git a/drivers/hv/mshv_synic.c b/drivers/hv/mshv_synic.c index f8b0337cdc82..7d273766bdb5 100644 --- a/drivers/hv/mshv_synic.c +++ b/drivers/hv/mshv_synic.c @@ -454,46 +454,72 @@ int mshv_synic_init(unsigned int cpu) #ifdef HYPERVISOR_CALLBACK_VECTOR union hv_synic_sint sint; #endif - union hv_synic_scontrol sctrl; struct hv_synic_pages *spages =3D this_cpu_ptr(mshv_root.synic_pages); struct hv_message_page **msg_page =3D &spages->hyp_synic_message_page; struct hv_synic_event_flags_page **event_flags_page =3D &spages->synic_event_flags_page; struct hv_synic_event_ring_page **event_ring_page =3D &spages->synic_event_ring_page; + /* VMBus runs on L1VH and nested root; it owns SIMP/SIEFP/SCONTROL */ + bool vmbus_active =3D !hv_root_partition() || hv_nested; =20 - /* Setup the Synic's message page */ + /* + * Map the SYNIC message page. When VMBus is not active the + * hypervisor pre-provisions the SIMP GPA but may not set + * simp_enabled =E2=80=94 enable it here. + */ simp.as_uint64 =3D hv_get_non_nested_msr(HV_MSR_SIMP); - simp.simp_enabled =3D true; + if (!vmbus_active) { + simp.simp_enabled =3D true; + hv_set_non_nested_msr(HV_MSR_SIMP, simp.as_uint64); + } *msg_page =3D memremap(simp.base_simp_gpa << HV_HYP_PAGE_SHIFT, HV_HYP_PAGE_SIZE, MEMREMAP_WB); =20 if (!(*msg_page)) - return -EFAULT; + goto cleanup_simp; =20 - hv_set_non_nested_msr(HV_MSR_SIMP, simp.as_uint64); - - /* Setup the Synic's event flags page */ + /* + * Map the event flags page. Same as SIMP: enable when + * VMBus is not active, already enabled by VMBus otherwise. + */ siefp.as_uint64 =3D hv_get_non_nested_msr(HV_MSR_SIEFP); - siefp.siefp_enabled =3D true; + if (!vmbus_active) { + siefp.siefp_enabled =3D true; + hv_set_non_nested_msr(HV_MSR_SIEFP, siefp.as_uint64); + } *event_flags_page =3D memremap(siefp.base_siefp_gpa << PAGE_SHIFT, PAGE_SIZE, MEMREMAP_WB); =20 if (!(*event_flags_page)) - goto cleanup; - - hv_set_non_nested_msr(HV_MSR_SIEFP, siefp.as_uint64); + goto cleanup_siefp; =20 /* Setup the Synic's event ring page */ sirbp.as_uint64 =3D hv_get_non_nested_msr(HV_MSR_SIRBP); - sirbp.sirbp_enabled =3D true; - *event_ring_page =3D memremap(sirbp.base_sirbp_gpa << PAGE_SHIFT, - PAGE_SIZE, MEMREMAP_WB); =20 - if (!(*event_ring_page)) - goto cleanup; + if (hv_root_partition()) { + *event_ring_page =3D memremap(sirbp.base_sirbp_gpa << PAGE_SHIFT, + PAGE_SIZE, MEMREMAP_WB); =20 + if (!(*event_ring_page)) + goto cleanup_siefp; + } else { + /* + * On L1VH the hypervisor does not provide a SIRBP page. + * Allocate one and program its GPA into the MSR. + */ + *event_ring_page =3D (struct hv_synic_event_ring_page *) + get_zeroed_page(GFP_KERNEL); + + if (!(*event_ring_page)) + goto cleanup_siefp; + + sirbp.base_sirbp_gpa =3D virt_to_phys(*event_ring_page) + >> PAGE_SHIFT; + } + + sirbp.sirbp_enabled =3D true; hv_set_non_nested_msr(HV_MSR_SIRBP, sirbp.as_uint64); =20 #ifdef HYPERVISOR_CALLBACK_VECTOR @@ -515,28 +541,30 @@ int mshv_synic_init(unsigned int cpu) sint.as_uint64); #endif =20 - /* Enable global synic bit */ - sctrl.as_uint64 =3D hv_get_non_nested_msr(HV_MSR_SCONTROL); - sctrl.enable =3D 1; - hv_set_non_nested_msr(HV_MSR_SCONTROL, sctrl.as_uint64); + /* When VMBus is active it already enabled SCONTROL. */ + if (!vmbus_active) { + union hv_synic_scontrol sctrl; + + sctrl.as_uint64 =3D hv_get_non_nested_msr(HV_MSR_SCONTROL); + sctrl.enable =3D 1; + hv_set_non_nested_msr(HV_MSR_SCONTROL, sctrl.as_uint64); + } =20 return 0; =20 -cleanup: - if (*event_ring_page) { - sirbp.sirbp_enabled =3D false; - hv_set_non_nested_msr(HV_MSR_SIRBP, sirbp.as_uint64); - memunmap(*event_ring_page); - } - if (*event_flags_page) { +cleanup_siefp: + if (*event_flags_page) + memunmap(*event_flags_page); + if (!vmbus_active) { siefp.siefp_enabled =3D false; hv_set_non_nested_msr(HV_MSR_SIEFP, siefp.as_uint64); - memunmap(*event_flags_page); } - if (*msg_page) { +cleanup_simp: + if (*msg_page) + memunmap(*msg_page); + if (!vmbus_active) { simp.simp_enabled =3D false; hv_set_non_nested_msr(HV_MSR_SIMP, simp.as_uint64); - memunmap(*msg_page); } =20 return -EFAULT; @@ -545,16 +573,15 @@ int mshv_synic_init(unsigned int cpu) int mshv_synic_cleanup(unsigned int cpu) { union hv_synic_sint sint; - union hv_synic_simp simp; - union hv_synic_siefp siefp; union hv_synic_sirbp sirbp; - union hv_synic_scontrol sctrl; struct hv_synic_pages *spages =3D this_cpu_ptr(mshv_root.synic_pages); struct hv_message_page **msg_page =3D &spages->hyp_synic_message_page; struct hv_synic_event_flags_page **event_flags_page =3D &spages->synic_event_flags_page; struct hv_synic_event_ring_page **event_ring_page =3D &spages->synic_event_ring_page; + /* VMBus runs on L1VH and nested root; it owns SIMP/SIEFP/SCONTROL */ + bool vmbus_active =3D !hv_root_partition() || hv_nested; =20 /* Disable the interrupt */ sint.as_uint64 =3D hv_get_non_nested_msr(HV_MSR_SINT0 + HV_SYNIC_INTERCEP= TION_SINT_INDEX); @@ -568,28 +595,47 @@ int mshv_synic_cleanup(unsigned int cpu) hv_set_non_nested_msr(HV_MSR_SINT0 + HV_SYNIC_DOORBELL_SINT_INDEX, sint.as_uint64); =20 - /* Disable Synic's event ring page */ + /* Disable SYNIC event ring page owned by MSHV */ sirbp.as_uint64 =3D hv_get_non_nested_msr(HV_MSR_SIRBP); sirbp.sirbp_enabled =3D false; - hv_set_non_nested_msr(HV_MSR_SIRBP, sirbp.as_uint64); - memunmap(*event_ring_page); =20 - /* Disable Synic's event flags page */ - siefp.as_uint64 =3D hv_get_non_nested_msr(HV_MSR_SIEFP); - siefp.siefp_enabled =3D false; - hv_set_non_nested_msr(HV_MSR_SIEFP, siefp.as_uint64); + if (hv_root_partition()) { + hv_set_non_nested_msr(HV_MSR_SIRBP, sirbp.as_uint64); + memunmap(*event_ring_page); + } else { + sirbp.base_sirbp_gpa =3D 0; + hv_set_non_nested_msr(HV_MSR_SIRBP, sirbp.as_uint64); + free_page((unsigned long)*event_ring_page); + } + + /* + * Release our mappings of the message and event flags pages. + * When VMBus is not active, we enabled SIMP/SIEFP =E2=80=94 disable + * them. Otherwise VMBus owns the MSRs =E2=80=94 leave them. + */ memunmap(*event_flags_page); + if (!vmbus_active) { + union hv_synic_simp simp; + union hv_synic_siefp siefp; =20 - /* Disable Synic's message page */ - simp.as_uint64 =3D hv_get_non_nested_msr(HV_MSR_SIMP); - simp.simp_enabled =3D false; - hv_set_non_nested_msr(HV_MSR_SIMP, simp.as_uint64); + siefp.as_uint64 =3D hv_get_non_nested_msr(HV_MSR_SIEFP); + siefp.siefp_enabled =3D false; + hv_set_non_nested_msr(HV_MSR_SIEFP, siefp.as_uint64); + + simp.as_uint64 =3D hv_get_non_nested_msr(HV_MSR_SIMP); + simp.simp_enabled =3D false; + hv_set_non_nested_msr(HV_MSR_SIMP, simp.as_uint64); + } memunmap(*msg_page); =20 - /* Disable global synic bit */ - sctrl.as_uint64 =3D hv_get_non_nested_msr(HV_MSR_SCONTROL); - sctrl.enable =3D 0; - hv_set_non_nested_msr(HV_MSR_SCONTROL, sctrl.as_uint64); + /* When VMBus is active it owns SCONTROL =E2=80=94 leave it. */ + if (!vmbus_active) { + union hv_synic_scontrol sctrl; + + sctrl.as_uint64 =3D hv_get_non_nested_msr(HV_MSR_SCONTROL); + sctrl.enable =3D 0; + hv_set_non_nested_msr(HV_MSR_SCONTROL, sctrl.as_uint64); + } =20 return 0; } --=20 2.43.0 From nobody Mon Apr 6 15:26:03 2026 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5B73E35BDDC; Fri, 3 Apr 2026 19:06:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775243184; cv=none; b=d0XDLoAzJr30TJ/4rxn4Io2PYOX5VqK8v5T4QxeeMx8hWXpaX5mEiOE1w6zm4I+K1LOV5gUdaX7ozR0oqI3rtAnRn1+nepBgkYHu44ZjL2vjeWc6KTQdblCcT/INKQXz3lblslBSW2DIrHSt4L1rAcaLoTKmyHUXqlj7LdSvxIE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775243184; c=relaxed/simple; bh=Oz1uz7dAG/uy72PvrmHa/5jl/z6xN5LT5cGFKSNgkTA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=af1Xi7ztwmX+6fX1QcFFNxEh6tf7YJghAyxs08DR+ZfwgGKWu55yU4pzKs3tfozQFnGUtqsYRVXFK0eklGn6JRTITwmy2LtzfG06Rd5M2+dNsVvaPiLxFad+HULH5nC3k2e0xl17l3hPh0fVe3TKXi3/weBH4NP2lTkMUvIqApE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=kNSVa9Kh; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="kNSVa9Kh" Received: by linux.microsoft.com (Postfix, from userid 1241) id 4B16B20B6F1B; Fri, 3 Apr 2026 12:06:23 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 4B16B20B6F1B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1775243183; bh=FlLuRtFSyNeb7uNmEQyawZmHGTy6mdwgcVGZEcmm/NY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kNSVa9Khjn0KGn4hrAjlF6ArDf69UDvLSGUnQOe+DE84NBziWHIjM6K/GFuzljp6F hGTo8QDOcbqyMRstGStqJS2D9vM+ls/5c9Sms/56GCbE2z3sJwO1Jy5t993dNJMfmK CphjhhesuyFkaTUv2Yw5ua3tcT1DA8BoNwRWIlTM= From: Jork Loeser To: linux-hyperv@vger.kernel.org Cc: x86@kernel.org, "K . Y . Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Arnd Bergmann , Michael Kelley , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Jork Loeser Subject: [PATCH v2 5/6] mshv: clean up SynIC state on kexec for L1VH Date: Fri, 3 Apr 2026 12:06:11 -0700 Message-ID: <20260403190613.47026-6-jloeser@linux.microsoft.com> X-Mailer: git-send-email 2.43.7 In-Reply-To: <20260403190613.47026-1-jloeser@linux.microsoft.com> References: <20260403190613.47026-1-jloeser@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Register the mshv reboot notifier for all parent partitions, not just root. Previously the notifier was gated on hv_root_partition(), so on L1VH (where hv_root_partition() is false) SINT0, SINT5, and SIRBP were never cleaned up before kexec. The kexec'd kernel then inherited stale unmasked SINTs and an enabled SIRBP pointing to freed memory. The L1VH SIRBP also needs special handling: unlike the root partition where the hypervisor provides the SIRBP page, L1VH must allocate its own page and program the GPA into the MSR. Add this allocation to mshv_synic_init() and the corresponding free to mshv_synic_cleanup(). Remove the unnecessary mshv_root_partition_init/exit wrappers and register the reboot notifier directly in mshv_parent_partition_init(). Make mshv_reboot_nb static since it no longer needs external linkage. Signed-off-by: Jork Loeser --- drivers/hv/mshv_root_main.c | 21 ++++----------------- 1 file changed, 4 insertions(+), 17 deletions(-) diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c index e6509c980763..281f530b68a9 100644 --- a/drivers/hv/mshv_root_main.c +++ b/drivers/hv/mshv_root_main.c @@ -2256,20 +2256,10 @@ static int mshv_reboot_notify(struct notifier_block= *nb, return 0; } =20 -struct notifier_block mshv_reboot_nb =3D { +static struct notifier_block mshv_reboot_nb =3D { .notifier_call =3D mshv_reboot_notify, }; =20 -static void mshv_root_partition_exit(void) -{ - unregister_reboot_notifier(&mshv_reboot_nb); -} - -static int __init mshv_root_partition_init(struct device *dev) -{ - return register_reboot_notifier(&mshv_reboot_nb); -} - static int __init mshv_init_vmm_caps(struct device *dev) { int ret; @@ -2339,8 +2329,7 @@ static int __init mshv_parent_partition_init(void) if (ret) goto remove_cpu_state; =20 - if (hv_root_partition()) - ret =3D mshv_root_partition_init(dev); + ret =3D register_reboot_notifier(&mshv_reboot_nb); if (ret) goto remove_cpu_state; =20 @@ -2368,8 +2357,7 @@ static int __init mshv_parent_partition_init(void) deinit_root_scheduler: root_scheduler_deinit(); exit_partition: - if (hv_root_partition()) - mshv_root_partition_exit(); + unregister_reboot_notifier(&mshv_reboot_nb); remove_cpu_state: cpuhp_remove_state(mshv_cpuhp_online); free_synic_pages: @@ -2387,8 +2375,7 @@ static void __exit mshv_parent_partition_exit(void) misc_deregister(&mshv_dev); mshv_irqfd_wq_cleanup(); root_scheduler_deinit(); - if (hv_root_partition()) - mshv_root_partition_exit(); + unregister_reboot_notifier(&mshv_reboot_nb); cpuhp_remove_state(mshv_cpuhp_online); free_percpu(mshv_root.synic_pages); } --=20 2.43.0 From nobody Mon Apr 6 15:26:03 2026 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E49953D75DE; Fri, 3 Apr 2026 19:06:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775243186; cv=none; b=ZQMsvqHxlu1a153fhy7DyO00bAmI9lxWokN/6/PqzllIw/xQpOwRypqwJGiQjWWteLuhpVT/KlEnfHruxqMpFtvXl+6mluY0KHVfqDfv7TXtiZ2AB8qaOtgeDJH94HzxaGx38l6SFdiLcj7fnnr3ivzfTs7vfhU7W2WEzKhNXXw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775243186; c=relaxed/simple; bh=eJFkaRo9CKhZlto6iDCuLzjnu9hkc3JVC3IjFHx3XJ0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=osO2NVXq7ijGgvRM634u3ox5Yem2vwcBBtoeSIoZjFde8v8oAqGitGh6uTDQ/0QP02z+TFoMaS7jSQVCJ+Dh7tXQVyHvMXJ0hMsjXTyGgImBS/xVOJ9neaIAoGi3M48YL/zS3J0Az+2qcVM8O+hvuTzmPQ/znPIB5zJdxgrDQDk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=HrXi5Jo4; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="HrXi5Jo4" Received: by linux.microsoft.com (Postfix, from userid 1241) id B41D120B6F1F; Fri, 3 Apr 2026 12:06:24 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com B41D120B6F1F DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1775243184; bh=dtJ8seWmbMqGCQ41xKmiIdEUtLNh0z2d7AxXL8JOv/0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HrXi5Jo4aCtNeQjWW2ySDzF7PLp8VHraU4yAPuAZNZz+1bcBauCDK4A8pW+KSU3dN 7/Po/OVE7lqy/GljJjK3eaLJaoH9Om3iDBykRNAa6KhHkWcRJPzMC1EIG4xnjE0z2s lPR2kiba0B72qk93okoNmRPeIBahvHN6/nsdr1wc= From: Jork Loeser To: linux-hyperv@vger.kernel.org Cc: x86@kernel.org, "K . Y . Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Arnd Bergmann , Michael Kelley , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Jork Loeser Subject: [PATCH v2 6/6] mshv: unmap debugfs stats pages on kexec Date: Fri, 3 Apr 2026 12:06:12 -0700 Message-ID: <20260403190613.47026-7-jloeser@linux.microsoft.com> X-Mailer: git-send-email 2.43.7 In-Reply-To: <20260403190613.47026-1-jloeser@linux.microsoft.com> References: <20260403190613.47026-1-jloeser@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" On L1VH, debugfs stats pages are overlay pages: the kernel allocates them and registers the GPAs with the hypervisor via HVCALL_MAP_STATS_PAGE2. These overlay mappings persist in the hypervisor across kexec. If the kexec'd kernel reuses those physical pages, the hypervisor's overlay semantics cause a machine check exception. Fix this by calling mshv_debugfs_exit() from the reboot notifier, which issues HVCALL_UNMAP_STATS_PAGE for each mapped stats page before kexec. This releases the overlay bindings so the physical pages can be safely reused. Guard mshv_debugfs_exit() against being called when init failed. Signed-off-by: Jork Loeser --- drivers/hv/mshv_debugfs.c | 7 ++++++- drivers/hv/mshv_root_main.c | 1 + 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/hv/mshv_debugfs.c b/drivers/hv/mshv_debugfs.c index ebf2549eb44d..f9a4499cf8f3 100644 --- a/drivers/hv/mshv_debugfs.c +++ b/drivers/hv/mshv_debugfs.c @@ -676,8 +676,10 @@ int __init mshv_debugfs_init(void) =20 mshv_debugfs =3D debugfs_create_dir("mshv", NULL); if (IS_ERR(mshv_debugfs)) { + err =3D PTR_ERR(mshv_debugfs); + mshv_debugfs =3D NULL; pr_err("%s: failed to create debugfs directory\n", __func__); - return PTR_ERR(mshv_debugfs); + return err; } =20 if (hv_root_partition()) { @@ -712,6 +714,9 @@ int __init mshv_debugfs_init(void) =20 void mshv_debugfs_exit(void) { + if (!mshv_debugfs) + return; + mshv_debugfs_parent_partition_remove(); =20 if (hv_root_partition()) { diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c index 281f530b68a9..7038fd830646 100644 --- a/drivers/hv/mshv_root_main.c +++ b/drivers/hv/mshv_root_main.c @@ -2252,6 +2252,7 @@ root_scheduler_deinit(void) static int mshv_reboot_notify(struct notifier_block *nb, unsigned long code, void *unused) { + mshv_debugfs_exit(); cpuhp_remove_state(mshv_cpuhp_online); return 0; } --=20 2.43.0