From nobody Tue Dec 23 14:20:22 2025 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 9CBFE10E6; Sun, 3 Mar 2024 08:09:09 +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=1709453351; cv=none; b=oyhqdgVWfmtoUdTjGBP2ImE6NfGuKkIfJr7TYmV/jsmMeUJbqqfWtyrrOsN1LSihzeJU0wO7Z4KBd0KZl24cl9MNywcrRpC64iGH9sijZrctldfEnWwo/KYpVJqPjBSFIsikLWcFBReF+GHDQYJMfLP+8vZ4pcIz1F3eFlLztOI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709453351; c=relaxed/simple; bh=ivElpwwJNVf3hcpUOWwZJYI9eam2vDVE9K7L0MERDe8=; h=From:To:Cc:Subject:Date:Message-Id; b=uaoa744XhRtT0B4QrcIlGI10a9c9/Rz9wN3YSfya/HYA3rrovtg8J9muypyYKK9LjvoqitTVO8ESIHGUDOa8QZyVgYyHFeYU4JtAnbSqwQIcMre6SpG+u5GcPa4VvznlsE17kh+529r3Znxu0CsR+oMBQLYEYtvAqVAKIrGYj34= 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=OIsDPnXO; 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="OIsDPnXO" Received: from linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net (linux.microsoft.com [13.77.154.182]) by linux.microsoft.com (Postfix) with ESMTPSA id 8AC4020B74C0; Sun, 3 Mar 2024 00:01:40 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 8AC4020B74C0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1709452900; bh=vUSOzIGgBi9vYkWUcajyjOx2gIH11Ew6VEiuY9yENd0=; h=From:To:Cc:Subject:Date:From; b=OIsDPnXOkFlauUZSv9FIsebaC3NeqaZU/thWQfGuhz77QVgm/yh44AQzvm4GJR5tb kv/ZsCnLU79/5y9Zug5jS6sxtY7wzRD5YAke3RCKSo+XS6uSGQ+nyin7AyjR18Rcix 3/g1Xwfz8FjhP3W9eHM3HIwk2xBoSWZs2ybvzlv0= From: Saurabh Sengar To: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, dwmw@amazon.co.uk, peterz@infradead.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org Cc: ssengar@microsoft.com, mhklinux@outlook.com Subject: [PATCH v3] x86/hyperv: Use per cpu initial stack for vtl context Date: Sun, 3 Mar 2024 00:01:36 -0800 Message-Id: <1709452896-13342-1-git-send-email-ssengar@linux.microsoft.com> X-Mailer: git-send-email 1.8.3.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Currently, the secondary CPUs in Hyper-V VTL context lack support for parallel startup. Therefore, relying on the single initial_stack fetched from the current task structure suffices for all vCPUs. However, common initial_stack risks stack corruption when parallel startup is enabled. In order to facilitate parallel startup, use the initial_stack from the per CPU idle thread instead of the current task. Fixes: 18415f33e2ac ("cpu/hotplug: Allow "parallel" bringup up to CPUHP_BP_= KICK_AP_STATE") Signed-off-by: Saurabh Sengar Reviewed-by: Michael Kelley --- [V3] - Added the VTL code dependency on SMP to fix kernel build error when SMP is disabled. arch/x86/hyperv/hv_vtl.c | 19 +++++++++++++++---- drivers/hv/Kconfig | 1 + 2 files changed, 16 insertions(+), 4 deletions(-) diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c index 804b629ea49d..b4e233954d0f 100644 --- a/arch/x86/hyperv/hv_vtl.c +++ b/arch/x86/hyperv/hv_vtl.c @@ -12,6 +12,7 @@ #include #include #include +#include <../kernel/smpboot.h> =20 extern struct boot_params boot_params; static struct real_mode_header hv_vtl_real_mode_header; @@ -58,7 +59,7 @@ static void hv_vtl_ap_entry(void) ((secondary_startup_64_fn)secondary_startup_64)(&boot_params, &boot_param= s); } =20 -static int hv_vtl_bringup_vcpu(u32 target_vp_index, u64 eip_ignored) +static int hv_vtl_bringup_vcpu(u32 target_vp_index, int cpu, u64 eip_ignor= ed) { u64 status; int ret =3D 0; @@ -72,7 +73,9 @@ static int hv_vtl_bringup_vcpu(u32 target_vp_index, u64 e= ip_ignored) struct ldttss_desc *ldt; struct desc_struct *gdt; =20 - u64 rsp =3D current->thread.sp; + struct task_struct *idle =3D idle_thread_get(cpu); + u64 rsp =3D (unsigned long)idle->thread.sp; + u64 rip =3D (u64)&hv_vtl_ap_entry; =20 native_store_gdt(&gdt_ptr); @@ -199,7 +202,15 @@ static int hv_vtl_apicid_to_vp_id(u32 apic_id) =20 static int hv_vtl_wakeup_secondary_cpu(u32 apicid, unsigned long start_eip) { - int vp_id; + int vp_id, cpu; + + /* Find the logical CPU for the APIC ID */ + for_each_present_cpu(cpu) { + if (arch_match_cpu_phys_id(cpu, apicid)) + break; + } + if (cpu >=3D nr_cpu_ids) + return -EINVAL; =20 pr_debug("Bringing up CPU with APIC ID %d in VTL2...\n", apicid); vp_id =3D hv_vtl_apicid_to_vp_id(apicid); @@ -213,7 +224,7 @@ static int hv_vtl_wakeup_secondary_cpu(u32 apicid, unsi= gned long start_eip) return -EINVAL; } =20 - return hv_vtl_bringup_vcpu(vp_id, start_eip); + return hv_vtl_bringup_vcpu(vp_id, cpu, start_eip); } =20 int __init hv_vtl_early_init(void) diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig index 00242107d62e..862c47b191af 100644 --- a/drivers/hv/Kconfig +++ b/drivers/hv/Kconfig @@ -16,6 +16,7 @@ config HYPERV config HYPERV_VTL_MODE bool "Enable Linux to boot in VTL context" depends on X86_64 && HYPERV + depends on SMP default n help Virtual Secure Mode (VSM) is a set of hypervisor capabilities and --=20 2.34.1