[PATCH 5.10 043/142] KVM: x86: allow KVM_REQ_GET_NESTED_STATE_PAGES outside guest mode for VMX

Greg Kroah-Hartman
2021-02-02T19:59:03Z

From: Paolo Bonzini <pbonzini@redhat.com>

commit 9a78e15802a87de2b08dfd1bd88e855201d2c8fa upstream.

VMX also uses KVM_REQ_GET_NESTED_STATE_PAGES for the Hyper-V eVMCS,
which may need to be loaded outside guest mode. Therefore we cannot
WARN in that case.

However, that part of nested_get_vmcs12_pages is _not_ needed at
vmentry time. Split it out of KVM_REQ_GET_NESTED_STATE_PAGES handling,
so that both vmentry and migration (and in the latter case, independent
of is_guest_mode) do the parts that are needed.

Cc: <stable@vger.kernel.org> # 5.10.x: f2c7ef3ba: KVM: nSVM: cancel KVM_REQ_GET_NESTED_STATE_PAGES
Cc: <stable@vger.kernel.org> # 5.10.x
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kvm/svm/nested.c | 3 +++
arch/x86/kvm/vmx/nested.c | 31 +++++++++++++++++++++++++------
arch/x86/kvm/x86.c | 4 +---
3 files changed, 29 insertions(+), 9 deletions(-)

--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -200,6 +200,9 @@ static bool svm_get_nested_state_pages(s
{
struct vcpu_svm *svm = to_svm(vcpu);

+ if (WARN_ON(!is_guest_mode(vcpu)))
+ return true;
+
if (!nested_svm_vmrun_msrpm(svm)) {
vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
vcpu->run->internal.suberror =
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3123,13 +3123,9 @@ static int nested_vmx_check_vmentry_hw(s
return 0;
}

-static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
+static bool nested_get_evmcs_page(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;

/*
* hv_evmcs may end up being not mapped after migration (when
@@ -3152,6 +3148,17 @@ static bool nested_get_vmcs12_pages(stru
}
}

+ return true;
+}
+
+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_cpu_has2(vmcs12, SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) {
/*
* Translate L1 physical address to host physical
@@ -3220,6 +3227,18 @@ static bool nested_get_vmcs12_pages(stru
exec_controls_setbit(vmx, CPU_BASED_USE_MSR_BITMAPS);
else
exec_controls_clearbit(vmx, CPU_BASED_USE_MSR_BITMAPS);
+
+ 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;
+
return true;
}

@@ -6575,7 +6594,7 @@ 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,
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8750,9 +8750,7 @@ static int vcpu_enter_guest(struct kvm_v

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;
}