The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

Possible dependencies:

50b2d49bafa1 ("KVM: x86: Inject #UD on emulated XSETBV if XSAVES isn't enabled") 92f9895c146d ("KVM: x86: Move XSETBV emulation to common code") 63129754178c ("KVM: SVM: Pass struct kvm_vcpu to exit handlers (and many, many other places)") 2a32a77cefa6 ("KVM: SVM: merge update_cr0_intercept into svm_set_cr0") 11f0cbf0c605 ("KVM: nSVM: Trace VM-Enter consistency check failures") 6906e06db9b0 ("KVM: nSVM: Add missing checks for reserved bits to svm_set_nested_state()") c08f390a75c1 ("KVM: nSVM: only copy L1 non-VMLOAD/VMSAVE data in svm_set_nested_state()") 9e8f0fbfff1a ("KVM: nSVM: rename functions and variables according to vmcbXY nomenclature") 193015adf40d ("KVM: nSVM: Track the ASID generation of the vmcb vmrun through the vmcb") af18fa775d07 ("KVM: nSVM: Track the physical cpu of the vmcb vmrun through the vmcb") 4995a3685f1b ("KVM: SVM: Use a separate vmcb for the nested L2 guest") 6d1b867d0456 ("KVM: SVM: Don't strip the C-bit from CR2 on #PF interception") 43c11d91fb1e ("KVM: x86: to track if L1 is running L2 VM") 9e46f6c6c959 ("KVM: SVM: Clear the CR4 register on reset") 2df8d3807ce7 ("KVM: SVM: Fix nested VM-Exit on #GP interception handling") d2df592fd8c6 ("KVM: nSVM: prepare guest save area while is_guest_mode is true") a04aead144fd ("KVM: nSVM: fix running nested guests when npt=0") 996ff5429e98 ("KVM: x86: move kvm_inject_gp up from kvm_set_dr to callers") e6c804a848d6 ("KVM: SVM: Move AVIC vCPU kicking snippet to helper function") ca29e14506bd ("KVM: x86: SEV: Treat C-bit as legal GPA bit regardless of vCPU mode")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 50b2d49bafa16e6311ab2da82f5aafc5f9ada99b Mon Sep 17 00:00:00 2001 From: Sean Christopherson seanjc@google.com Date: Wed, 24 Aug 2022 03:30:57 +0000 Subject: [PATCH] KVM: x86: Inject #UD on emulated XSETBV if XSAVES isn't enabled

Inject #UD when emulating XSETBV if CR4.OSXSAVE is not set. This also covers the "XSAVE not supported" check, as setting CR4.OSXSAVE=1 #GPs if XSAVE is not supported (and userspace gets to keep the pieces if it forces incoherent vCPU state).

Add a comment to kvm_emulate_xsetbv() to call out that the CPU checks CR4.OSXSAVE before checking for intercepts. AMD'S APM implies that #UD has priority (says that intercepts are checked before #GP exceptions), while Intel's SDM says nothing about interception priority. However, testing on hardware shows that both AMD and Intel CPUs prioritize the #UD over interception.

Fixes: 02d4160fbd76 ("x86: KVM: add xsetbv to the emulator") Cc: stable@vger.kernel.org Cc: Vitaly Kuznetsov vkuznets@redhat.com Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20220824033057.3576315-4-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index d5ec3a2ed5a4..aacb28c83e43 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -4132,6 +4132,9 @@ static int em_xsetbv(struct x86_emulate_ctxt *ctxt) { u32 eax, ecx, edx;

+ if (!(ctxt->ops->get_cr(ctxt, 4) & X86_CR4_OSXSAVE)) + return emulate_ud(ctxt); + eax = reg_read(ctxt, VCPU_REGS_RAX); edx = reg_read(ctxt, VCPU_REGS_RDX); ecx = reg_read(ctxt, VCPU_REGS_RCX); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c95cf18a796c..b0c47b41c264 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1065,6 +1065,7 @@ static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)

int kvm_emulate_xsetbv(struct kvm_vcpu *vcpu) { + /* Note, #UD due to CR4.OSXSAVE=0 has priority over the intercept. */ if (static_call(kvm_x86_get_cpl)(vcpu) != 0 || __kvm_set_xcr(vcpu, kvm_rcx_read(vcpu), kvm_read_edx_eax(vcpu))) { kvm_inject_gp(vcpu, 0);