linmiaohe <linmiaohe@xxxxxxxxxx> writes:
> 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)
With Sean's comment added the subject of the patch is a bit unexpected
:-) But the change itself looks good (and thanks Sean for the great
explanation!).
Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
--
Vitaly
