From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Fix some typos in the comments. Also fix coding style.
[Sean Christopherson rewrites the comment of write_fault_to_shadow_pgtable
field in struct kvm_vcpu_arch.]
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
---
v1->v2:
Use Sean Christopherson' comment for write_fault_to_shadow_pgtable
---
arch/x86/include/asm/kvm_host.h | 16 +++++++++++++---
arch/x86/kvm/vmx/nested.c | 5 +++--
2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 4dffbc10d3f8..40a0c0fd95ca 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -781,9 +781,19 @@ struct kvm_vcpu_arch {
u64 msr_kvm_poll_control;
/*
- * Indicate whether the access faults on its page table in guest
- * which is set when fix page fault and used to detect unhandeable
- * instruction.
+ * Indicates the guest is trying to write a gfn that contains one or
+ * more of the PTEs used to translate the write itself, i.e. the access
+ * is changing its own translation in the guest page tables. KVM exits
+ * to userspace if emulation of the faulting instruction fails and this
+ * flag is set, as KVM cannot make forward progress.
+ *
+ * If emulation fails for a write to guest page tables, KVM unprotects
+ * (zaps) the shadow page for the target gfn and resumes the guest to
+ * retry the non-emulatable instruction (on hardware). Unprotecting the
+ * gfn doesn't allow forward progress for a self-changing access because
+ * doing so also zaps the translation for the gfn, i.e. retrying the
+ * instruction will hit a !PRESENT fault, which results in a new shadow
+ * page and sends KVM back to square one.
*/
bool write_fault_to_shadow_pgtable;
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 657c2eda357c..e7faebccd733 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -544,7 +544,8 @@ static void nested_vmx_disable_intercept_for_msr(unsigned long *msr_bitmap_l1,
}
}
-static inline void enable_x2apic_msr_intercepts(unsigned long *msr_bitmap) {
+static inline void enable_x2apic_msr_intercepts(unsigned long *msr_bitmap)
+{
int msr;
for (msr = 0x800; msr <= 0x8ff; msr += BITS_PER_LONG) {
@@ -1981,7 +1982,7 @@ static int nested_vmx_handle_enlightened_vmptrld(struct kvm_vcpu *vcpu,
}
/*
- * Clean fields data can't de used on VMLAUNCH and when we switch
+ * Clean fields data can't be used on VMLAUNCH and when we switch
* between different L2 guests as KVM keeps a single VMCS12 per L1.
*/
if (from_launch || evmcs_gpa_changed)
--
2.19.1
