Introduce a helper to directly fault-in a TDP page without going through the full page fault path. This allows SEV-SNP to build the netsted-page-table while handling the page state change VMGEXIT. A guest may issue a page state change VMGEXIT before accessing the page. Creating a fault-in, we can get the TDP page level and PFN which will be used while calculating the RMP page size.
SEV-SNP guest calls, page state change VMGEXIT followed by the PVALIDATE. If the page is not present in the TDP then PVALIDATE will cause a nested page fault. If we can build the TDP while handling the page state change VMGEXIT, it can also avoid a nested page fault due to the page not being present. Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Joerg Roedel <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Tony Luck <[email protected]> Cc: Dave Hansen <[email protected]> Cc: "Peter Zijlstra (Intel)" <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Tom Lendacky <[email protected]> Cc: David Rientjes <[email protected]> Cc: Sean Christopherson <[email protected]> Cc: [email protected] Cc: [email protected] Signed-off-by: Brijesh Singh <[email protected]> --- arch/x86/kvm/mmu.h | 2 ++ arch/x86/kvm/mmu/mmu.c | 20 ++++++++++++++++++++ 2 files changed, 22 insertions(+) diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index 261be1d2032b..70dce26a5882 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -109,6 +109,8 @@ static inline void kvm_mmu_load_pgd(struct kvm_vcpu *vcpu) int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, bool prefault); +int kvm_mmu_map_tdp_page(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, int max_level); + static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u32 err, bool prefault) { diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index e55df7b4e297..33104943904b 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3808,6 +3808,26 @@ int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, max_level, true); } +int kvm_mmu_map_tdp_page(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, int max_level) +{ + int r; + + /* + * Loop on the page fault path to handle the case where an mmu_notifier + * invalidation triggers RET_PF_RETRY. In the normal page fault path, + * KVM needs to resume the guest in case the invalidation changed any + * of the page fault properties, i.e. the gpa or error code. For this + * path, the gpa and error code are fixed by the caller, and the caller + * expects failure if and only if the page fault can't be fixed. + */ + do { + r = direct_page_fault(vcpu, gpa, error_code, false, max_level, true); + } while (r == RET_PF_RETRY); + + return r; +} +EXPORT_SYMBOL_GPL(kvm_mmu_map_tdp_page); + static void nonpaging_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *context) { -- 2.17.1
