Re: [PATCH RESEND v4 5/9] KVM: VMX: Add init/set/get functions for SPP

Vitaly Kuznetsov
2019-08-14T12:43:44Z

Yang Weijiang <weijiang.yang@intel.com> writes:

> init_spp() must be called before {get, set}_subpage
> functions, it creates subpage access bitmaps for memory pages
> and issues a KVM request to setup SPPT root pages.
>
> kvm_mmu_set_subpages() is to enable SPP bit in EPT leaf page
> and setup corresponding SPPT entries. The mmu_lock
> is held before above operation. If it's called in EPT fault and
> SPPT mis-config induced handler, mmu_lock is acquired outside
> the function, otherwise, it's acquired inside it.
>
> kvm_mmu_get_subpages() is used to query access bitmap for
> protected page, it's also used in EPT fault handler to check
> whether the fault EPT page is SPP protected as well.
>
> Co-developed-by: He Chen <he.chen@linux.intel.com>
> Signed-off-by: He Chen <he.chen@linux.intel.com>
> Co-developed-by: Zhang Yi <yi.z.zhang@linux.intel.com>
> Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com>
> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> ---
> arch/x86/include/asm/kvm_host.h | 18 ++++
> arch/x86/include/asm/vmx.h | 2 +
> arch/x86/kvm/mmu.c | 160 ++++++++++++++++++++++++++++++++
> arch/x86/kvm/vmx/vmx.c | 48 ++++++++++
> arch/x86/kvm/x86.c | 40 ++++++++
> include/linux/kvm_host.h | 4 +-
> include/uapi/linux/kvm.h | 9 ++
> 7 files changed, 280 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 44f6e1757861..5c4882015acc 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -398,8 +398,13 @@ struct kvm_mmu {
> void (*invlpg)(struct kvm_vcpu *vcpu, gva_t gva, hpa_t root_hpa);
> void (*update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
> u64 *spte, const void *pte);
> + int (*get_subpages)(struct kvm *kvm, struct kvm_subpage *spp_info);
> + int (*set_subpages)(struct kvm *kvm, struct kvm_subpage *spp_info);
> + int (*init_spp)(struct kvm *kvm);
> +
> hpa_t root_hpa;
> gpa_t root_cr3;
> + hpa_t sppt_root;

(I'm sorry if this was previously discussed, I didn't look into previous
submissions).

What happens when we launch a nested guest and switch vcpu->arch.mmu to
point at arch.guest_mmu? sppt_root will point to INVALID_PAGE and SPP
won't be enabled in VMCS?

(I'm sorry again, I'm likely missing something obvious)

--
Vitaly