From nobody Sat Feb 7 14:39:33 2026 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 8C82417BCD; Fri, 2 Feb 2024 07:12:50 +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=1706857971; cv=none; b=VRCv9YtnO1/IuW+o+Y1hMBVI6jOzQmsZHK0Uu0erQAn2gNiuwfUTY5lH9Grgm0l6SCiO1wPbyzIXJvaL3hXpoxMsDrb7j7KDnkukywsVJU7XxB2NzqfufZB9LrIjUqYBpIvV+3keOzDoSC4NaRuv/JtZnAdwqB42hpeGuOrdyAs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706857971; c=relaxed/simple; bh=OXJcTTtmB7mC8LGM63buUTanubcADvLhLibsbVoC900=; h=From:To:Cc:Subject:Date:Message-Id; b=UzQs8Z9oZSfTsD2MfU2+FWpfR+krN5vECbI/Z6lIhUqQD0NQIA0nAwciEA1AYthJ3ecY2t0NEN5znPynUebAWwA3h7BVne6sLbjAho7HsOIqKUF4GVZ4Iph1Qmxi1LqXgru0U5pqrjEIqcd3R0Vgtfncxhv+s6s2YJ7L0q22j0Y= 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=eypSXRLh; 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="eypSXRLh" Received: from linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net (linux.microsoft.com [13.77.154.182]) by linux.microsoft.com (Postfix) with ESMTPSA id 0B26020B2000; Thu, 1 Feb 2024 23:12:50 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 0B26020B2000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1706857970; bh=R5u/o9X7wtbTC+FTLZo+7zWFnW6hVfTvEu5yxIcwaUM=; h=From:To:Cc:Subject:Date:From; b=eypSXRLhHoOO3GKUNF+boHveRs81hoSKCuhIQoKJGEbt3UQIJH7fUL0nwBMhxkfx+ 5ByylJbQcVKI1ZB6XWu8YEKVpU3Z13sg/lFKf7Mcnxh/kwGIEk104ARK9QPh69Hm9x FEAU0H3Elx7GeZdWrvSjtKRccUdcvIO7yfhfAlRY= 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 Subject: [PATCH v2] x86/hyperv: Use per cpu initial stack for vtl context Date: Thu, 1 Feb 2024 23:12:37 -0800 Message-Id: <1706857957-13857-1-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 --- arch/x86/hyperv/hv_vtl.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c index 96e6c51515f5..b0ab724def17 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; @@ -57,7 +58,7 @@ 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; @@ -71,7 +72,8 @@ 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); @@ -198,7 +200,15 @@ 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); @@ -212,7 +222,7 @@ 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) --=20 2.34.1