From patchwork Tue Mar 18 01:31:11 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yan Zhao X-Patchwork-Id: 14020149 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 633657DA95; Tue, 18 Mar 2025 01:35:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.19 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742261728; cv=none; b=u9kBgbbxjwGlcJnHvZowaDQggsRXdLWiUme/BV359tfaGioyByKHcTWsoT0h4CM+soc8hINjE00YOuMM+xaBxx2WQvHa4iLWHQmXogyYBvwlkGVPps/6zziGZPxrhBkebxzv3oKVsBMDHctJeGTJZ7E3yzAzFYbrKjEDMzJCRpg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742261728; c=relaxed/simple; bh=NwOAx5+dxnQzBsBey2xQSL2X0FYSBltO7FxvfjiIzGI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=amB4a7V7ODegivhzvLq2OkvGk1oYJnxcOZ1UZdf6qTazbMgRgw3ZFIMQpMi2EpbROMCt4zF0tdzc6V6woykdmlUgA7aqK9kX5NdVF8x7J5UeYoHd/YtB/yGSuZaXokUy2J05ynVMxFG+72RkqdiRCtvEVjUSQOZWoHubMaCJAQU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=cODzODeD; arc=none smtp.client-ip=192.198.163.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="cODzODeD" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1742261727; x=1773797727; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=NwOAx5+dxnQzBsBey2xQSL2X0FYSBltO7FxvfjiIzGI=; b=cODzODeDdb4JJFbz9uIjAwovKd1P3a9FOIhTLAIt7fbZQdQvB9HSGPQ6 vKG6BW/SVXK4jji+KZJno4Rq+MZSMBwZoCus4yb/ie/U+007+6+q52GCR qyxK+vPsALpeWG1UAviE1J4zokxcfBvzEJXKMdBjoSXXQ9PSiHg8rprBR 2lLLTVbRDUpshw/i9WGSfzLtir5UjIiFURPS3lZjn43nfxMvwSe0wEWbR Bhk9rZx7prJy9gMUltwxJjPoChpFGKxMSaGaqyu70ORTZBQal2QEXyGDd rxuroRyC5AZdAASeQy9DPk47BgJMTZJZifDRlUxuK0h3R57yqHCJuWlBr A==; X-CSE-ConnectionGUID: Uay7iiDdRXqOkB5RknVR2A== X-CSE-MsgGUID: rlhHD+ehSuKYeVKnQaVFHg== X-IronPort-AV: E=McAfee;i="6700,10204,11376"; a="42556046" X-IronPort-AV: E=Sophos;i="6.14,255,1736841600"; d="scan'208";a="42556046" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2025 18:35:27 -0700 X-CSE-ConnectionGUID: S/fEzu+6Q+im8JVS/vbgUA== X-CSE-MsgGUID: RTb5KkJlSuS1fUqap6gR8Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.14,255,1736841600"; d="scan'208";a="122284291" Received: from yzhao56-desk.sh.intel.com ([10.239.159.62]) by fmviesa008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2025 18:33:00 -0700 From: Yan Zhao To: pbonzini@redhat.com, seanjc@google.com Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Yan Zhao Subject: [PATCH v2 1/5] KVM: x86/mmu: Further check old SPTE is leaf for spurious prefetch fault Date: Tue, 18 Mar 2025 09:31:11 +0800 Message-ID: <20250318013111.5648-1-yan.y.zhao@intel.com> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20250318013038.5628-1-yan.y.zhao@intel.com> References: <20250318013038.5628-1-yan.y.zhao@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Instead of simply treating a prefetch fault as spurious when there's a shadow-present old SPTE, further check if the old SPTE is leaf to determine if a prefetch fault is spurious. It's not reasonable to treat a prefetch fault as spurious when there's a shadow-present non-leaf SPTE without a corresponding shadow-present leaf SPTE. e.g., in the following sequence, a prefetch fault should not be considered spurious: 1. add a memslot with size 4K 2. prefault GPA A in the memslot 3. delete the memslot (zap all disabled) 4. re-add the memslot with size 2M 5. prefault GPA A again. In step 5, the prefetch fault attempts to install a 2M huge entry. Since step 3 zaps the leaf SPTE for GPA A while keeping the non-leaf SPTE, the leaf entry will remain empty after step 5 if the fetch fault is regarded as spurious due to a shadow-present non-leaf SPTE. Signed-off-by: Yan Zhao --- arch/x86/kvm/mmu/mmu.c | 2 +- arch/x86/kvm/mmu/tdp_mmu.c | 3 ++- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 8160870398b9..94c677f8cc05 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -2846,7 +2846,7 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot, } if (is_shadow_present_pte(*sptep)) { - if (prefetch) + if (prefetch && is_last_spte(*sptep, level)) return RET_PF_SPURIOUS; /* diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 046b6ba31197..ab65fd915ef2 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -1137,7 +1137,8 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu, if (WARN_ON_ONCE(sp->role.level != fault->goal_level)) return RET_PF_RETRY; - if (fault->prefetch && is_shadow_present_pte(iter->old_spte)) + if (fault->prefetch && is_shadow_present_pte(iter->old_spte) && + is_last_spte(iter->old_spte, iter->level)) return RET_PF_SPURIOUS; if (is_shadow_present_pte(iter->old_spte) && From patchwork Tue Mar 18 01:32:10 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yan Zhao X-Patchwork-Id: 14020145 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.16]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 95B3B256D; Tue, 18 Mar 2025 01:33:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.16 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742261619; cv=none; b=InEcSPMd7hEeXzBP2xZpb2nBadpPxW5xN+l4C5DtH3IOT8Vza1r5ldJ13qTPeGviz+r+BmV8JuxVOoYKK7PjcRzv3EEwAoOZh485zfqHWnHGqmmo+1/1nhUUeMWoVmaP82xvxUXoyKk7oSXmCKi/N7Nogp15+WGh7xLcNmAm00k= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742261619; c=relaxed/simple; bh=PXdTvjKO9jrgad/pGh2EBWa191SiR6GvYLmT4pf8h8o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=oBm+TvfN/wuP7zWYcYMD51270HoANN9aA8qhqypZedvKTiximOfobpdrYSjFwNLhGr+W/0U7dBWrLjSsPxUx+KUTC78FL5gyGVQkj2LjTREcZNjupMuQZ9nS6x2vvasao7so6Kqw2KsdI4BKmsPKuPwrZTW6TERW0hw0lSjwWLI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=DdcJYygP; arc=none smtp.client-ip=192.198.163.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="DdcJYygP" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1742261617; x=1773797617; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=PXdTvjKO9jrgad/pGh2EBWa191SiR6GvYLmT4pf8h8o=; b=DdcJYygPPJjxCaaUN2PC6RxF8BJMcATb/9U4CyIoP1bClORLSmhjIIIj JkMgZbeeAxVvkIaWwcnqwi3uAL223P4IwAjHQ6iIf4mT6IABDe+ZXNqk3 iGZG+XXgkZzlsQ534poGdpGvdokNZmb1ePUp/qtmktwcJ9OyyI1/EAVcO T1cU65d6dHaffPeQFG+YyIllGS08rLJjSMyCAZMsg1KGmFDIEYXIByovF APeWrFWQ2zzL5jm5Hyagp6YvdwFNc2j3SgTZyNVoqopkjAbhqLD5PcsKa PKdyh2fxUfrB9p0EE1HUK9AE0zJ74BJ9L25heRrr5ydvYxEU3fheBpvUX g==; X-CSE-ConnectionGUID: OYvE5lg1SiSIO4HSL+k8iw== X-CSE-MsgGUID: pKfqyy0MQESZW6/ifjNqMw== X-IronPort-AV: E=McAfee;i="6700,10204,11376"; a="30964561" X-IronPort-AV: E=Sophos;i="6.14,255,1736841600"; d="scan'208";a="30964561" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by fmvoesa110.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2025 18:33:37 -0700 X-CSE-ConnectionGUID: CymqiyvaTJGLx2NR/rmWzA== X-CSE-MsgGUID: Y2QCO1HXSuaByq2AZzbfBw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.14,255,1736841600"; d="scan'208";a="121838316" Received: from yzhao56-desk.sh.intel.com ([10.239.159.62]) by orviesa009-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2025 18:33:34 -0700 From: Yan Zhao To: pbonzini@redhat.com, seanjc@google.com Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Yan Zhao Subject: [PATCH v2 2/5] KVM: x86/tdp_mmu: Merge prefetch and access checks for spurious faults Date: Tue, 18 Mar 2025 09:32:10 +0800 Message-ID: <20250318013210.5701-1-yan.y.zhao@intel.com> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20250318013038.5628-1-yan.y.zhao@intel.com> References: <20250318013038.5628-1-yan.y.zhao@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Combine prefetch and is_access_allowed() checks into a unified path to detect spurious faults, since both cases now share identical logic. No functional changes. Signed-off-by: Yan Zhao --- arch/x86/kvm/mmu/tdp_mmu.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index ab65fd915ef2..6365eb6c1390 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -1137,12 +1137,8 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu, if (WARN_ON_ONCE(sp->role.level != fault->goal_level)) return RET_PF_RETRY; - if (fault->prefetch && is_shadow_present_pte(iter->old_spte) && - is_last_spte(iter->old_spte, iter->level)) - return RET_PF_SPURIOUS; - if (is_shadow_present_pte(iter->old_spte) && - is_access_allowed(fault, iter->old_spte) && + (fault->prefetch || is_access_allowed(fault, iter->old_spte)) && is_last_spte(iter->old_spte, iter->level)) return RET_PF_SPURIOUS; From patchwork Tue Mar 18 01:32:38 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yan Zhao X-Patchwork-Id: 14020146 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C8B3F256D; Tue, 18 Mar 2025 01:34:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.9 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742261648; cv=none; b=hClhk/GBNX/4AkkdQ5WpfcwDQiaXwg1rb/nTzgkfzHPWuyyL168FCdq9B3MJAcIFhUaeO3O4q1RZ1+rBymM5ni1xL7LslJwNGQsiAjptM/8yegLQoqrfNf+wMnsAczVMuYhHBzGIbtc++rHkT03wh4zDmM4Z/fOiwFNv45lXt9k= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742261648; c=relaxed/simple; bh=3h/tBuBGetcnoP/gV+1yhxo0Nigtzof+XWtMFsLQMSU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=k58whTHOicDCTWG5f2bShwK0sbzasQ34fI2DSaXCcEaJWJwUnC0Ptiw98oKBqpGKA5IwTrsfjoD6yArcPxZJiLmUCJezv9lVQXSwInBB58d+8bW0wORkee2ZrSu8kX7wNqxvpMi+Ea6M5yvh5hl1ImcUBpQq0tdSJCTQLGL+4YY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=k60ijP0P; arc=none smtp.client-ip=192.198.163.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="k60ijP0P" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1742261647; x=1773797647; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=3h/tBuBGetcnoP/gV+1yhxo0Nigtzof+XWtMFsLQMSU=; b=k60ijP0Pl+OZbwM6M7bF+y8WPlsSus0fB3dedEZpCf6KyNDlwOk29aTD MJfnWu6brbdEJknaszkfFfBD0N6FS53xSIGMT84PTeHSR28q8A/4uOSsY Hje+/mL4PLcx4xpArkchZ4lxLmRWB/2pTlbOYKWadEAPBOV+Dy1r+Oimm wkjYG0TU2/SwiI+mZJf2eke6PyiuMmu0ATQ0J4aMRM1B4IlTO8U0YAMA4 54VaLd/zot+dadQ6ZlFDzfUvIgrohClLzhz1WoSc5IfL07nSRQNHKXasg jpSedmzT7gHYY9q0CNaBHNd02q1SacN78XqB5QTsYdLv6oitKvtu1j11v A==; X-CSE-ConnectionGUID: 1wiQHBadQrG5pdWhUyGiGg== X-CSE-MsgGUID: kwft7VtvTq6hq0Whrk3TDw== X-IronPort-AV: E=McAfee;i="6700,10204,11376"; a="54009451" X-IronPort-AV: E=Sophos;i="6.14,255,1736841600"; d="scan'208";a="54009451" Received: from orviesa005.jf.intel.com ([10.64.159.145]) by fmvoesa103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2025 18:34:05 -0700 X-CSE-ConnectionGUID: 55Wb8WbjQXusR/PcHCAi0Q== X-CSE-MsgGUID: m9oVNe38RomUnnrlFYFT0g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.14,255,1736841600"; d="scan'208";a="127283965" Received: from yzhao56-desk.sh.intel.com ([10.239.159.62]) by orviesa005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2025 18:34:04 -0700 From: Yan Zhao To: pbonzini@redhat.com, seanjc@google.com Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Yan Zhao Subject: [PATCH v2 3/5] KVM: x86/tdp_mmu: WARN if PFN changes for spurious faults Date: Tue, 18 Mar 2025 09:32:38 +0800 Message-ID: <20250318013238.5732-1-yan.y.zhao@intel.com> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20250318013038.5628-1-yan.y.zhao@intel.com> References: <20250318013038.5628-1-yan.y.zhao@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Add a WARN() to assert that KVM does _not_ change the PFN of a shadow-present SPTE during spurious fault handling. KVM should _never_ change the PFN of a shadow-present SPTE and TDP MMU already BUG()s on this. However, spurious faults just return early before the existing BUG() could be hit. Suggested-by: Sean Christopherson Signed-off-by: Yan Zhao --- arch/x86/kvm/mmu/tdp_mmu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 6365eb6c1390..d219ecd4ac5b 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -1139,8 +1139,10 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu, if (is_shadow_present_pte(iter->old_spte) && (fault->prefetch || is_access_allowed(fault, iter->old_spte)) && - is_last_spte(iter->old_spte, iter->level)) + is_last_spte(iter->old_spte, iter->level)) { + WARN_ON_ONCE(fault->pfn != spte_to_pfn(iter->old_spte)); return RET_PF_SPURIOUS; + } if (unlikely(!fault->slot)) new_spte = make_mmio_spte(vcpu, iter->gfn, ACC_ALL); From patchwork Tue Mar 18 01:33:10 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yan Zhao X-Patchwork-Id: 14020147 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A12BC335C0; Tue, 18 Mar 2025 01:34:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.12 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742261679; cv=none; b=Gnd+UYO4dy99XSEr1ZYFe1QoPWxBj5Rws69JnQ/r1tVlCxYP+2mZACTtWF5vKDZF4quylb1RZjDm3GCwj44hx/Mdgnnp6nFrAJwgKOL5Shpk4s2liOBV0qiShG9aC31RAx9g10IJwBtg9HaDO89+odfuZkQMvkikhYxODhNZ+Rg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742261679; c=relaxed/simple; bh=vvkZUaLrHnUJHGxnetVQdXOSxMK2s/AEG29SSV0tqc0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HFyRPu74Q368/JpSxk710qOnVmBzb1ATaKUGnpek+Pq0MTtjof97S/ivDEDOHkHKsd/EFu2zGeCWJWqVsGrGdjOAmmbbdM77ezsIC0MvXR32lUIXm5lQHSJNx9KoOuqdNKXRI1rRA+G/JEsya2bClQ1cdVUK9i9NhgoRZWwsiWI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Hf+XGVFA; arc=none smtp.client-ip=192.198.163.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Hf+XGVFA" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1742261678; x=1773797678; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=vvkZUaLrHnUJHGxnetVQdXOSxMK2s/AEG29SSV0tqc0=; b=Hf+XGVFA2n5R2d42UH5nolEapapT6OVwgwsU/cUjSGq0WvX/20nOk7A/ 9f/eWw8JndEC9DkPMjamVGaPBr/ZZKaxM4c2yunfecoicc41e1qwBF5WA n+c8wXUTYIwpQmkmCreUQFizl8xpb3DxScQuEl7sdnLHxSiybqopvbpKP hSA9Fsarw9qm5txil1sfYm1LyFp/8oFp1mUCGHPOvjRrsoSpupiMa1baK w+ElmakP0JV7G/QdnltaVpM0adcG5Iyr5rhTqQRw4dXqEv5VzByfAjWv7 zh3Az6G7Cp6C+J0oLiRwUAsr0lwdXZxBMzkDu+Mmh5fhDzRBe0g6HLGCE A==; X-CSE-ConnectionGUID: 9XMKcNb6Tuagua1kwILeGA== X-CSE-MsgGUID: 6tvOL6YPSE2eWUrKlDuNOw== X-IronPort-AV: E=McAfee;i="6700,10204,11376"; a="47269874" X-IronPort-AV: E=Sophos;i="6.14,255,1736841600"; d="scan'208";a="47269874" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2025 18:34:37 -0700 X-CSE-ConnectionGUID: NDAEbuUDR2uGardIrFORsA== X-CSE-MsgGUID: fiedTt/KRaWdBpeKeQapgA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.14,255,1736841600"; d="scan'208";a="122131390" Received: from yzhao56-desk.sh.intel.com ([10.239.159.62]) by fmviesa007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2025 18:34:35 -0700 From: Yan Zhao To: pbonzini@redhat.com, seanjc@google.com Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Yan Zhao Subject: [PATCH v2 4/5] KVM: x86/mmu: Warn if PFN changes on shadow-present SPTE in shadow MMU Date: Tue, 18 Mar 2025 09:33:10 +0800 Message-ID: <20250318013310.5781-1-yan.y.zhao@intel.com> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20250318013038.5628-1-yan.y.zhao@intel.com> References: <20250318013038.5628-1-yan.y.zhao@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Warn if PFN changes on shadow-present SPTE in mmu_set_spte(). KVM should _never_ change the PFN of a shadow-present SPTE. In mmu_set_spte(), there is a WARN_ON_ONCE() on pfn changes on shadow-present SPTE in mmu_spte_update() to detect this condition. However, that WARN_ON_ONCE() is not hittable since mmu_set_spte() invokes drop_spte() earlier before mmu_spte_update(), which clears SPTE to a !shadow-present state. So, before invoking drop_spte(), add a WARN_ON_ONCE() in mmu_set_spte() to warn PFN change of a shadow-present SPTE. For the spurious prefetch fault, only return RET_PF_SPURIOUS directly when PFN is not changed. When PFN changes, fall through to follow the sequence of drop_spte(), warn of PFN change, make_spte(), flush tlb, rmap_add(). Signed-off-by: Yan Zhao --- arch/x86/kvm/mmu/mmu.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 94c677f8cc05..607cbb19ea96 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -2846,7 +2846,8 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot, } if (is_shadow_present_pte(*sptep)) { - if (prefetch && is_last_spte(*sptep, level)) + if (prefetch && is_last_spte(*sptep, level) && + pfn == spte_to_pfn(*sptep)) return RET_PF_SPURIOUS; /* @@ -2860,7 +2861,7 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot, child = spte_to_child_sp(pte); drop_parent_pte(vcpu->kvm, child, sptep); flush = true; - } else if (pfn != spte_to_pfn(*sptep)) { + } else if (WARN_ON_ONCE(pfn != spte_to_pfn(*sptep))) { drop_spte(vcpu->kvm, sptep); flush = true; } else From patchwork Tue Mar 18 01:33:33 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yan Zhao X-Patchwork-Id: 14020148 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9201D3FC2; Tue, 18 Mar 2025 01:34:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.9 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742261701; cv=none; b=su3voaj7lV/Tg757FBtgu831Sru5QzyuPy6xpu5Rfoz1cNUFHaCf9cyH8zsa3c4FhqYWhus5bNZbinNZtZnoDyq0yyNXoQYXtytDoNslfWbHXXxB+94RwERXJcyTvNtYDKxzUAy7L6q0rXhD3faU73q7TIkY7aw2thfm+0XibDk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742261701; c=relaxed/simple; bh=pLa7nmBIJgWzueqkPk4AGuMVC9d7jDDRLX/NlIBoDkQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rR8dTBbhycszZCaw83CyIea1BYKJjq+5mOl0fANvEved1s9cKkgtbvCHyOkUi1izdy49LkE06M5g7tKdpZMWOx7S6FjlIXl6PQZPK0/Mz7uY0YtKtCTEL/TGwXvKT9ubM5ZuAE5PJb08tQkSmUlwRKVQs6GWOZc8vguu9zz7Br0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=OvVBJbPJ; arc=none smtp.client-ip=192.198.163.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="OvVBJbPJ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1742261699; x=1773797699; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=pLa7nmBIJgWzueqkPk4AGuMVC9d7jDDRLX/NlIBoDkQ=; b=OvVBJbPJkR/m4ylhBtL2MKFUzIzvhfoN0fqjRwqvXSwb9pe9LIp5BmPE j+uCrXLtKGg4CZPpJ3veK8ytqshoXxZuwywv7o94awrvQr0vOfYIUoIaz z3BVt8SAwj+c0WHXZaH9fb4DT+Npn/jU47z9FQu853rmPsexCUgC1TCTo Zit8fAbZvlaNUFZynDHLH+4DEwdL0374LSLDYOYRkkA9wRTaSLOwme6ZP ywGSa7VbYTrv3yg+4tXfhsn+Hn8neBoajIWLqfh+eb/8NhqedKD/2zlSU E1vzjboSggSA+k2ijgu1Wu8Y7TV0XMW68chqLCG12SzN6Pm4nePz0cUiw A==; X-CSE-ConnectionGUID: Opk93W7WQmq3+K/FC3CCBw== X-CSE-MsgGUID: xRFtpcyeQla3gHhonYOaow== X-IronPort-AV: E=McAfee;i="6700,10204,11376"; a="54009598" X-IronPort-AV: E=Sophos;i="6.14,255,1736841600"; d="scan'208";a="54009598" Received: from orviesa005.jf.intel.com ([10.64.159.145]) by fmvoesa103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2025 18:34:59 -0700 X-CSE-ConnectionGUID: P78im2mWSXK+g/BfK4CEXA== X-CSE-MsgGUID: MOrFEG6sR8iuttfa+EO9kA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.14,255,1736841600"; d="scan'208";a="127284151" Received: from yzhao56-desk.sh.intel.com ([10.239.159.62]) by orviesa005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2025 18:34:57 -0700 From: Yan Zhao To: pbonzini@redhat.com, seanjc@google.com Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Yan Zhao Subject: [PATCH v2 5/5] KVM: x86/mmu: Check and free obsolete roots in kvm_mmu_reload() Date: Tue, 18 Mar 2025 09:33:33 +0800 Message-ID: <20250318013333.5817-1-yan.y.zhao@intel.com> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20250318013038.5628-1-yan.y.zhao@intel.com> References: <20250318013038.5628-1-yan.y.zhao@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Check request KVM_REQ_MMU_FREE_OBSOLETE_ROOTS to free obsolete roots in kvm_mmu_reload() to prevent kvm_mmu_reload() from seeing a stale obsolete root. Since kvm_mmu_reload() can be called outside the vcpu_enter_guest() path (e.g., kvm_arch_vcpu_pre_fault_memory()), it may be invoked after a root has been marked obsolete and before vcpu_enter_guest() is invoked to process KVM_REQ_MMU_FREE_OBSOLETE_ROOTS and set root.hpa to invalid. This causes kvm_mmu_reload() to fail to load a new root, which can lead to kvm_arch_vcpu_pre_fault_memory() being stuck in the while loop in kvm_tdp_map_page() since RET_PF_RETRY is always returned due to is_page_fault_stale(). Keep the existing check of KVM_REQ_MMU_FREE_OBSOLETE_ROOTS in vcpu_enter_guest() since the cost of kvm_check_request() is negligible, especially a check that's guarded by kvm_request_pending(). Export symbol of kvm_mmu_free_obsolete_roots() as kvm_mmu_reload() is inline and may be called outside of kvm.ko. Suggested-by: Sean Christopherson Signed-off-by: Yan Zhao --- arch/x86/kvm/mmu.h | 3 +++ arch/x86/kvm/mmu/mmu.c | 1 + 2 files changed, 4 insertions(+) diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index 050a0e229a4d..f2b36d32ef40 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -104,6 +104,9 @@ void kvm_mmu_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, static inline int kvm_mmu_reload(struct kvm_vcpu *vcpu) { + if (kvm_check_request(KVM_REQ_MMU_FREE_OBSOLETE_ROOTS, vcpu)) + kvm_mmu_free_obsolete_roots(vcpu); + /* * Checking root.hpa is sufficient even when KVM has mirror root. * We can have either: diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 607cbb19ea96..15fd4838e4f2 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -5802,6 +5802,7 @@ void kvm_mmu_free_obsolete_roots(struct kvm_vcpu *vcpu) __kvm_mmu_free_obsolete_roots(vcpu->kvm, &vcpu->arch.root_mmu); __kvm_mmu_free_obsolete_roots(vcpu->kvm, &vcpu->arch.guest_mmu); } +EXPORT_SYMBOL_GPL(kvm_mmu_free_obsolete_roots); static u64 mmu_pte_write_fetch_gpte(struct kvm_vcpu *vcpu, gpa_t *gpa, int *bytes)