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From: Maxim Levitsky <mlevitsk@redhat.com>
To: kvm@vger.kernel.org
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Borislav Petkov <bp@alien8.de>, Bandan Das <bsd@redhat.com>,
	linux-kernel@vger.kernel.org (open list),
	Joerg Roedel <joro@8bytes.org>, Ingo Molnar <mingo@redhat.com>,
	Wei Huang <wei.huang2@amd.com>,
	Sean Christopherson <seanjc@google.com>,
	linux-kselftest@vger.kernel.org (open list:KERNEL SELFTEST
	FRAMEWORK), Maxim Levitsky <mlevitsk@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Jim Mattson <jmattson@google.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
	Shuah Khan <shuah@kernel.org>, Wanpeng Li <wanpengli@tencent.com>
Subject: [PATCH 03/14] KVM: x86: nSVM: test eax for 4K alignment for GP errata workaround
Date: Tue, 14 Sep 2021 18:48:14 +0300	[thread overview]
Message-ID: <20210914154825.104886-4-mlevitsk@redhat.com> (raw)
In-Reply-To: <20210914154825.104886-1-mlevitsk@redhat.com>

GP SVM errata workaround made the #GP handler always emulate
the SVM instructions.

However these instructions #GP in case the operand is not 4K aligned,
but the workaround code didn't check this and we ended up
emulating these instructions anyway.

This is only an emulation accuracy check bug as there is no harm for
KVM to read/write unaligned vmcb images.

Fixes: 82a11e9c6fa2 ("KVM: SVM: Add emulation support for #GP triggered by SVM instructions")

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
 arch/x86/kvm/svm/svm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index b2e710a3fff6..6645542df9bd 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2224,6 +2224,10 @@ static int gp_interception(struct kvm_vcpu *vcpu)
 	if (error_code)
 		goto reinject;
 
+	/* All SVM instructions expect page aligned RAX */
+	if (svm->vmcb->save.rax & ~PAGE_MASK)
+		goto reinject;
+
 	/* Decode the instruction for usage later */
 	if (x86_decode_emulated_instruction(vcpu, 0, NULL, 0) != EMULATION_OK)
 		goto reinject;
-- 
2.26.3


  parent reply	other threads:[~2021-09-14 15:49 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-14 15:48 [PATCH 00/14] nSVM fixes and optional features Maxim Levitsky
2021-09-14 15:48 ` [PATCH 01/14] KVM: x86: nSVM: restore int_vector in svm_clear_vintr Maxim Levitsky
2021-09-23 14:04   ` Paolo Bonzini
2021-09-14 15:48 ` [PATCH 02/14] KVM: x86: selftests: test simultaneous uses of V_IRQ from L1 and L0 Maxim Levitsky
2021-09-23 14:05   ` Paolo Bonzini
2021-09-14 15:48 ` Maxim Levitsky [this message]
2021-09-23 14:05   ` [PATCH 03/14] KVM: x86: nSVM: test eax for 4K alignment for GP errata workaround Paolo Bonzini
2021-09-14 15:48 ` [PATCH 04/14] KVM: x86: nSVM: don't copy pause related settings Maxim Levitsky
2021-09-14 15:48 ` [PATCH 05/14] KVM: x86: nSVM: don't copy virt_ext from vmcb12 Maxim Levitsky
2021-09-23 14:06   ` Paolo Bonzini
2021-09-14 15:48 ` [PATCH 06/14] KVM: x86: SVM: don't set VMLOAD/VMSAVE intercepts on vCPU reset Maxim Levitsky
2021-09-23 16:40   ` Paolo Bonzini
2021-09-14 15:48 ` [PATCH 07/14] KVM: x86: SVM: add warning for CVE-2021-3656 Maxim Levitsky
2021-09-23 16:44   ` Paolo Bonzini
2021-10-12  0:21     ` Sean Christopherson
2021-10-11 17:30   ` Xiaoyao Li
2021-10-12  7:51     ` Maxim Levitsky
2021-09-14 15:48 ` [PATCH 08/14] KVM: x86: SVM: add module param to control LBR virtualization Maxim Levitsky
2021-09-14 15:48 ` [PATCH 09/14] KVM: x86: nSVM: correctly virtualize LBR msrs when L2 is running Maxim Levitsky
2021-09-14 15:48 ` [PATCH 10/14] KVM: x86: nSVM: implement nested LBR virtualization Maxim Levitsky
2021-09-14 15:48 ` [PATCH 11/14] KVM: x86: nSVM: implement nested VMLOAD/VMSAVE Maxim Levitsky
2021-09-14 15:48 ` [PATCH 12/14] KVM: x86: SVM: add module param to control TSC scaling Maxim Levitsky
2021-09-14 15:48 ` [PATCH 13/14] KVM: x86: nSVM: implement nested " Maxim Levitsky
2021-09-14 15:48 ` [PATCH 14/14] KVM: x86: nSVM: support PAUSE filter threshold and count Maxim Levitsky
2021-09-23 16:54 ` [PATCH 00/14] nSVM fixes and optional features Paolo Bonzini

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