From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
f734222792@gmail.com, Vitaly Kuznetsov <vkuznets@redhat.com>,
Sashiko Bot <sashiko-bot@kernel.org>,
Yosry Ahmed <yosry@kernel.org>
Subject: [PATCH v4 02/17] KVM: nVMX: Make VMPTRST return eVMCS GPA when it is used
Date: Thu, 3 Sep 2026 17:24:08 -0700 [thread overview]
Message-ID: <20260904002423.3154436-3-seanjc@google.com> (raw)
In-Reply-To: <20260904002423.3154436-1-seanjc@google.com>
From: Vitaly Kuznetsov <vkuznets@redhat.com>
VMPTRST with active eVMCS is currently forbidden, however, returning 1
without skipping the instruction will likely result in L1 getting
stuck. While TLFS does not specify the expected behavior, genuine Hyper-V
seems to be returning eVMCS GPA. Implement the same behavior in KVM.
Reported-by: f734222792@gmail.com
Link: https://bugzilla.kernel.org/show_bug.cgi?id=221841
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/vmx/nested.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index ad3726fd4fda..3058efa65c82 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -5964,7 +5964,7 @@ static int handle_vmptrst(struct kvm_vcpu *vcpu)
{
unsigned long exit_qual = vmx_get_exit_qual(vcpu);
u32 instr_info = vmcs_read32(VMX_INSTRUCTION_INFO);
- gpa_t current_vmptr = to_vmx(vcpu)->nested.current_vmptr;
+ gpa_t current_vmptr;
struct x86_exception e;
gva_t gva;
int r;
@@ -5972,8 +5972,16 @@ static int handle_vmptrst(struct kvm_vcpu *vcpu)
if (!nested_vmx_check_permission(vcpu))
return 1;
- if (unlikely(nested_vmx_is_evmptr12_valid(to_vmx(vcpu))))
- return 1;
+ /*
+ * Hyper-V TLFS does not specify the behavior of VMPTRST when eVMCS is used
+ * but genuine Hyper-V seems to be returning eVMCS GPA.
+ */
+#ifdef CONFIG_KVM_HYPERV
+ if (nested_vmx_is_evmptr12_valid(to_vmx(vcpu)))
+ current_vmptr = to_vmx(vcpu)->nested.hv_evmcs_vmptr;
+ else
+#endif
+ current_vmptr = to_vmx(vcpu)->nested.current_vmptr;
if (get_vmx_mem_address(vcpu, exit_qual, instr_info,
true, sizeof(gpa_t), &gva))
--
2.55.0.979.g7e5102b832-goog
next prev parent reply other threads:[~2026-09-04 0:24 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-04 0:24 [PATCH v4 00/17] KVM: nVMX: Adjust VMPTRLD/VMPTRST behavior with active eVMCS Sean Christopherson
2026-09-04 0:24 ` [PATCH v4 01/17] KVM: nVMX: Make VMPTRLD result in #UD when eVMCS is used Sean Christopherson
2026-09-04 0:24 ` Sean Christopherson [this message]
2026-09-04 0:24 ` [PATCH v4 03/17] KVM: selftests: Don't clobber RFLAGS in happy path of __KVM_ASM_SAFE() Sean Christopherson
2026-09-04 0:24 ` [PATCH v4 04/17] KVM: selftests: Adapt to the updated VMPTRST behavior when eVMCS is used Sean Christopherson
2026-09-04 0:24 ` [PATCH v4 05/17] KVM: selftests: Check VMPTRLD with active eVMCS Sean Christopherson
2026-09-04 0:24 ` [PATCH v4 06/17] KVM: selftests: Assert success in vmptrst(), kill off vmptrstz() Sean Christopherson
2026-09-04 0:24 ` [PATCH v4 07/17] KVM: selftests: Always assert that vmxon() and prepare_for_vmx_operation() succeed Sean Christopherson
2026-09-04 0:24 ` [PATCH v4 08/17] KVM: selftests: Always assert that vmclear() succeeds Sean Christopherson
2026-09-04 0:24 ` [PATCH v4 09/17] KVM: selftests: Always assert that vmptrld() succeeds Sean Christopherson
2026-09-04 0:24 ` [PATCH v4 10/17] KVM: selftests: Drop useless return code from load_vmcs() Sean Christopherson
2026-09-04 0:24 ` [PATCH v4 11/17] KVM: selftests: Add macros to handle simple VMX instructions Sean Christopherson
2026-09-04 0:24 ` [PATCH v4 12/17] KVM: selftests: Drop dead return code from evmcs_vmptrld() and load_evmcs() Sean Christopherson
2026-09-04 0:24 ` [PATCH v4 13/17] KVM: selftests: Dedup assembly code for VMLAUNCH and VMRESUME Sean Christopherson
2026-09-04 0:24 ` [PATCH v4 14/17] KVM: selftests: Assert success in vmlaunch() and vmresume() Sean Christopherson
2026-09-04 0:35 ` sashiko-bot
2026-09-04 0:24 ` [PATCH v4 15/17] KVM: selftests: Add __vmwrite() and use it when initializing optional fields Sean Christopherson
2026-09-04 0:35 ` sashiko-bot
2026-09-11 15:55 ` Sean Christopherson
2026-09-04 0:24 ` [PATCH v4 16/17] KVM: selftests: Always assert that vmwrite() succeeds Sean Christopherson
2026-09-04 0:24 ` [PATCH v4 17/17] KVM: selftests: Always assert that vmreadz() succeeds Sean Christopherson
2026-09-04 0:36 ` sashiko-bot
2026-09-21 14:05 ` [PATCH v4 00/17] KVM: nVMX: Adjust VMPTRLD/VMPTRST behavior with active eVMCS Sean Christopherson
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