From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f54.google.com (mail-ej1-f54.google.com [209.85.218.54]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2028942C4FE for ; Wed, 29 Jul 2026 17:06:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.54 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785344796; cv=none; b=Wkgil/RsObOSd0gubg0OvVsrrAI5TTDrFIqUUp8Yn32hFTEhsw2grt9OreseW4YW2R228RWPUapIjoudWso4UaTaSXuN4GVVJCUu9oCAWQWn6UK8/cAt9YkS5laTA7xSV0qBHM+E3hbKogM5gh3wErMgNp6mLljtiIFpOUIWN0k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785344796; c=relaxed/simple; bh=qy1ZrS34HWYINmCJTbWiTbYunsqnbS5NGry799vrNGI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HpO5K87N8paz24CO11rSEANsh5u4NZZnKSw0prcV80a0spECCVrOU0QuJPKioY4caY/VtBSueMW1h8aUUUagK2ZUWBRrohk/wt+nuU/dQRU4P4cvUw6JOnZSoHbTJ7qwZcm43fk0Xd3tB/9QAW6UolCjt767RsqykjwiSVN/XkA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org; spf=pass smtp.mailfrom=chromium.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b=dwXMbekd; arc=none smtp.client-ip=209.85.218.54 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="dwXMbekd" Received: by mail-ej1-f54.google.com with SMTP id a640c23a62f3a-c1c24ec9525so205928166b.1 for ; Wed, 29 Jul 2026 10:06:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1785344793; x=1785949593; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=TulM3ZhdLtGxFX94kWWm5LHhn5poNeK8dkvPkUfs8Zo=; b=dwXMbekdRxCxyvFO8D3xiQ+bWElTD0o7Qny378MzL9rpQPAajD0fagRQ40k9btwq/f 5sVVVkpHol6Mak20kWBgrv8iC0UqFO1Zyt0/HEbgXUt49WHaZ2VbUFavSuIbgpWPAkGD Mj/g1ggIYlOFX7UJb8fWos56u+QGKgAWKr7Pg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785344793; x=1785949593; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=TulM3ZhdLtGxFX94kWWm5LHhn5poNeK8dkvPkUfs8Zo=; b=PJHnVMLXTRSraUGyvwarPaWK8rqWwA0GBgM6D0xctwRMQTbqCUccx/L1Kpm8cyzO09 aplboOcmrnv9mFKn3r+WnW5bRTl3QZbamBJ2KnH/SH15OfCYeybchMZCEnDxcYEXaW/z DdDCd7CzKqnD2vv9JXyoUvwj+Os8fPW2hDPldB3OXRsoczvzap5rlbc/OI1hisRHYof5 myiG9zJOpZhafwqv2wRijWzMUxD1G5yuklXIy1j0+5whTmEpW1jjhkTobFZu9lCoCKLz mRmqeKyT8V4kcXPEO+4otShtXZOS+zMR3gRWqTEoUoIupzo61HvIGtX1DTbsYj0waUjl xMGQ== X-Forwarded-Encrypted: i=1; AHgh+RrXw2kzvJ6PTKFsd0PK0O3CamVd23FECBKz59QDhlaYsDVcU6fD7ev3n0BxNvynbpe3I06qDUR8Je2ng9Y=@vger.kernel.org X-Gm-Message-State: AOJu0Yyyg6j0kqdDDMtnIXnCF5oszf+vcDLkoOHwVGAgkbO9xtbZl+MR 1B81Mb7laVtRcvdj0icLWZMpVQWI9vNqNmbjvJBmmMNrYjY1pyQZkQjYChKc12c+1g== X-Gm-Gg: AR+sD11ZpBhOywOvw39YF1Z8XzAWkfkQhCAuhAHoEpiwxi/Ubo6cpYmQs65YiGQQmNX 3LJBoiBtXCuBmh0K2Gca6JpS3ElMvhudU/D0UbLpk6jctIE6pn8uj9zSzHL4py97pfuKUpJfRKG EE8rOvk0I/WoVM8PrrHkBCaNsnQ7KIuGJCmGsvvjHnwsL/6oHgY4pvyH7MZgHS3HvF/oKs88Wqq xclk+Y2LkmxjsdCR7v+Zg7DNUikw9wyLKEaThmDH5EyTEuIu86Mb+/prS83eu3r1zB2n4+v+KGv 6E5FH967p6cArWn7fVM0IWmIR/n6MNxzxv3ESScEf2nv48Cjei1wqXh6Qfp6C0cZcvsNuA4Dqxs tCHsdzZvc4K/7Jmn9dvj3PXZ+51g8KqR0E/NJvZoCkW/KFCzq95QDzNj11/MQoWVXsEMwWhpwuk RjGdvG2bDbdLv4Zzu5bwCaD2TeCD4P/bNeAzCyiR2YfIepmT04ODKqBaDOdxIMCevi/N3UUa7i0 MVjhtZIZP/gPbGpWF9tYKY8JMlxyZ6dfHt3M5iMVGSoWBY/+OgJWQU= X-Received: by 2002:a17:907:7a89:b0:c1f:6f31:37c3 with SMTP id a640c23a62f3a-c1f7218a993mr407297266b.54.1785344793273; Wed, 29 Jul 2026 10:06:33 -0700 (PDT) Received: from dmaluka.c.googlers.com.com (110.121.148.146.bc.googleusercontent.com. [146.148.121.110]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c1f83c686a8sm142753566b.4.2026.07.29.10.06.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Jul 2026 10:06:32 -0700 (PDT) From: Dmytro Maluka To: Sean Christopherson Cc: Paolo Bonzini , Dave Hansen , Chao Gao , Kai Huang , Naveen N Rao , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Vineeth Pillai , Chuanxiao Dong , Aashish Sharma , Grzegorz Jaszczyk , Dmytro Maluka Subject: [PATCH v2 2/2] KVM: VMX: Fix stale PID-pointer table entry left after vCPU free Date: Wed, 29 Jul 2026 17:06:21 +0000 Message-ID: <20260729170621.308809-3-dmaluka@chromium.org> X-Mailer: git-send-email 2.55.0.508.g3f0d502094-goog In-Reply-To: <20260729170621.308809-1-dmaluka@chromium.org> References: <20260729170621.308809-1-dmaluka@chromium.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit vCPU creation in kvm_vm_ioctl_create_vcpu() may fail after kvm_arch_vcpu_create() -> vmx_vcpu_create() already succeeded. In such case kvm_vm_ioctl_create_vcpu() destroys the newly created vCPU in the failure path. However, that leaves a side effect: the IPIv pid_table entry remains configured with this vCPU's pi_desc address. As a result, when another vCPU sends an IPI to the APIC ID of this failed-to-create vCPU, it will cause HW to write to this (freed!) pi_desc memory. [*] Fix this by clearing the pid_table entry when destroying the vCPU. Note that the same issue exists for SVM AVIC as well [1], to be fixed. [*] Although, since this memory is freed into the kvm_vcpu_cache kmem cache which is only used for allocating kvm_vcpus, _maybe_ this memory will only be reused for pi_desc of another vCPU, not for anything else. So _maybe_ this will only result in delivering the IPI to a wrong vCPU (possibly of another VM) in the worst case, not in a random corruption of kernel memory. [1] https://lore.kernel.org/kvm/al4rNqpBYy8FGKPw@blrnaveerao1/ Signed-off-by: Dmytro Maluka --- arch/x86/kvm/vmx/vmx.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index cc75feec05da..f98c268b5150 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -7665,6 +7665,9 @@ void vmx_vcpu_free(struct kvm_vcpu *vcpu) nested_vmx_free_vcpu(vcpu); free_loaded_vmcs(vmx->loaded_vmcs); free_page((unsigned long)vmx->ve_info); + + if (vmx_can_use_ipiv(vcpu)) + WRITE_ONCE(to_kvm_vmx(vcpu->kvm)->pid_table[vcpu->vcpu_id], 0); } int vmx_vcpu_create(struct kvm_vcpu *vcpu) -- 2.55.0.508.g3f0d502094-goog