Re: [PATCH] KVM: x86: allow KVM_REQ_GET_NESTED_STATE_PAGES outside guest mode for VMX
From: Sean Christopherson <seanjc@google.com>
Date: 2021-01-26 10:11:46
Also in:
lkml, stable
On Mon, Jan 25, 2021, Paolo Bonzini wrote:
quoted hunk ↗ jump to hunk
+static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu) +{ + struct vmcs12 *vmcs12 = get_vmcs12(vcpu); + struct vcpu_vmx *vmx = to_vmx(vcpu); + struct kvm_host_map *map; + struct page *page; + u64 hpa; + + if (!nested_get_evmcs_page(vcpu)) + return false; if (nested_cpu_has2(vmcs12, SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) { /*@@ -3224,6 +3233,17 @@ static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu) return true; } +static bool vmx_get_nested_state_pages(struct kvm_vcpu *vcpu) +{ + if (!nested_get_evmcs_page(vcpu)) + return false; + + if (is_guest_mode(vcpu) && !nested_get_vmcs12_pages(vcpu)) + return false;
nested_get_evmcs_page() will get called twice in the common case of is_guest_mode() == true. I can't tell if that will ever be fatal, but it's definitely weird. Maybe this? if (!is_guest_mode(vcpu)) return nested_get_evmcs_page(vcpu); return nested_get_vmcs12_pages(vcpu);
quoted hunk ↗ jump to hunk
+ + return true; +} + static int nested_vmx_write_pml_buffer(struct kvm_vcpu *vcpu, gpa_t gpa) { struct vmcs12 *vmcs12;@@ -6602,7 +6622,7 @@ struct kvm_x86_nested_ops vmx_nested_ops = { .hv_timer_pending = nested_vmx_preemption_timer_pending, .get_state = vmx_get_nested_state, .set_state = vmx_set_nested_state, - .get_nested_state_pages = nested_get_vmcs12_pages, + .get_nested_state_pages = vmx_get_nested_state_pages, .write_log_dirty = nested_vmx_write_pml_buffer, .enable_evmcs = nested_enable_evmcs, .get_evmcs_version = nested_get_evmcs_version,diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 9a8969a6dd06..b910aa74ee05 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c@@ -8802,9 +8802,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (kvm_request_pending(vcpu)) { if (kvm_check_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu)) { - if (WARN_ON_ONCE(!is_guest_mode(vcpu))) - ; - else if (unlikely(!kvm_x86_ops.nested_ops->get_nested_state_pages(vcpu))) { + if (unlikely(!kvm_x86_ops.nested_ops->get_nested_state_pages(vcpu))) { r = 0; goto out; }-- 2.26.2