From c2fe3cd4604ac87c587db05d41843d667dc43815 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 6 Oct 2020 18:44:15 -0700 Subject: KVM: x86: Move vendor CR4 validity check to dedicated kvm_x86_ops hook Split out VMX's checks on CR4.VMXE to a dedicated hook, .is_valid_cr4(), and invoke the new hook from kvm_valid_cr4(). This fixes an issue where KVM_SET_SREGS would return success while failing to actually set CR4. Fixing the issue by explicitly checking kvm_x86_ops.set_cr4()'s return in __set_sregs() is not a viable option as KVM has already stuffed a variety of vCPU state. Note, kvm_valid_cr4() and is_valid_cr4() have different return types and inverted semantics. This will be remedied in a future patch. Fixes: 5e1746d6205d ("KVM: nVMX: Allow setting the VMXE bit in CR4") Signed-off-by: Sean Christopherson Message-Id: <20201007014417.29276-5-sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/nested.c | 2 +- arch/x86/kvm/vmx/vmx.c | 31 ++++++++++++++++++------------- arch/x86/kvm/vmx/vmx.h | 2 +- 3 files changed, 20 insertions(+), 15 deletions(-) (limited to 'arch/x86/kvm/vmx') diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 89af692deb7e..efebd849b3c9 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -4814,7 +4814,7 @@ static int handle_vmon(struct kvm_vcpu *vcpu) /* * The Intel VMX Instruction Reference lists a bunch of bits that are * prerequisite to running VMXON, most notably cr4.VMXE must be set to - * 1 (see vmx_set_cr4() for when we allow the guest to set this). + * 1 (see vmx_is_valid_cr4() for when we allow the guest to set this). * Otherwise, we should fail with #UD. But most faulting conditions * have already been checked by hardware, prior to the VM-exit for * VMXON. We do test guest cr4.VMXE because processor CR4 always has diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index d9a4526c730c..3327964a1e2e 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -3095,7 +3095,23 @@ static void vmx_load_mmu_pgd(struct kvm_vcpu *vcpu, unsigned long pgd, vmcs_writel(GUEST_CR3, guest_cr3); } -int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) +static bool vmx_is_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) +{ + /* + * We operate under the default treatment of SMM, so VMX cannot be + * enabled under SMM. Note, whether or not VMXE is allowed at all is + * handled by kvm_valid_cr4(). + */ + if ((cr4 & X86_CR4_VMXE) && is_smm(vcpu)) + return false; + + if (to_vmx(vcpu)->nested.vmxon && !nested_cr4_valid(vcpu, cr4)) + return false; + + return true; +} + +void vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) { struct vcpu_vmx *vmx = to_vmx(vcpu); /* @@ -3123,17 +3139,6 @@ int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) } } - /* - * We operate under the default treatment of SMM, so VMX cannot be - * enabled under SMM. Note, whether or not VMXE is allowed at all is - * handled by kvm_valid_cr4(). - */ - if ((cr4 & X86_CR4_VMXE) && is_smm(vcpu)) - return 1; - - if (vmx->nested.vmxon && !nested_cr4_valid(vcpu, cr4)) - return 1; - vcpu->arch.cr4 = cr4; kvm_register_mark_available(vcpu, VCPU_EXREG_CR4); @@ -3164,7 +3169,6 @@ int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) vmcs_writel(CR4_READ_SHADOW, cr4); vmcs_writel(GUEST_CR4, hw_cr4); - return 0; } void vmx_get_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg) @@ -7612,6 +7616,7 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = { .get_cpl = vmx_get_cpl, .get_cs_db_l_bits = vmx_get_cs_db_l_bits, .set_cr0 = vmx_set_cr0, + .is_valid_cr4 = vmx_is_valid_cr4, .set_cr4 = vmx_set_cr4, .set_efer = vmx_set_efer, .get_idt = vmx_get_idt, diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index f6f66e5c6510..9d3a557949ac 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -321,7 +321,7 @@ u32 vmx_get_interrupt_shadow(struct kvm_vcpu *vcpu); void vmx_set_interrupt_shadow(struct kvm_vcpu *vcpu, int mask); int vmx_set_efer(struct kvm_vcpu *vcpu, u64 efer); void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0); -int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4); +void vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4); void set_cr4_guest_host_mask(struct vcpu_vmx *vmx); void ept_save_pdptrs(struct kvm_vcpu *vcpu); void vmx_get_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg); -- cgit v1.2.3