Follow the recommendation from APM2 section 15.36.10 and 15.36.11 to resolve the RMP violation encountered during the NPT table walk. Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx> --- arch/x86/include/asm/kvm_host.h | 3 ++ arch/x86/kvm/mmu/mmu.c | 20 ++++++++++++ arch/x86/kvm/svm/sev.c | 57 +++++++++++++++++++++++++++++++++ arch/x86/kvm/svm/svm.c | 2 ++ arch/x86/kvm/svm/svm.h | 2 ++ 5 files changed, 84 insertions(+) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 46323af09995..117e2e08d7ed 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1399,6 +1399,9 @@ struct kvm_x86_ops { void (*write_page_begin)(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn); void (*write_page_end)(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn); + + int (*handle_rmp_page_fault)(struct kvm_vcpu *vcpu, gpa_t gpa, kvm_pfn_t pfn, + int level, u64 error_code); }; struct kvm_x86_nested_ops { diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index e60f54455cdc..b6a676ba1862 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -5096,6 +5096,18 @@ static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, write_unlock(&vcpu->kvm->mmu_lock); } +static int handle_rmp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code) +{ + kvm_pfn_t pfn; + int level; + + if (unlikely(!kvm_mmu_get_tdp_walk(vcpu, gpa, &pfn, &level))) + return RET_PF_RETRY; + + kvm_x86_ops.handle_rmp_page_fault(vcpu, gpa, pfn, level, error_code); + return RET_PF_RETRY; +} + int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code, void *insn, int insn_len) { @@ -5112,6 +5124,14 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code, goto emulate; } + if (unlikely(error_code & PFERR_GUEST_RMP_MASK)) { + r = handle_rmp_page_fault(vcpu, cr2_or_gpa, error_code); + if (r == RET_PF_RETRY) + return 1; + else + return r; + } + if (r == RET_PF_INVALID) { r = kvm_mmu_do_page_fault(vcpu, cr2_or_gpa, lower_32_bits(error_code), false); diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index d30419e91288..5b033d4c3b92 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -3497,3 +3497,60 @@ void sev_snp_write_page_begin(struct kvm *kvm, struct kvm_memory_slot *slot, gfn BUG_ON(rc != 0); } } + +int snp_handle_rmp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, kvm_pfn_t pfn, + int level, u64 error_code) +{ + struct rmpentry *e; + int rlevel, rc = 0; + bool private; + gfn_t gfn; + + e = snp_lookup_page_in_rmptable(pfn_to_page(pfn), &rlevel); + if (!e) + return 1; + + private = !!(error_code & PFERR_GUEST_ENC_MASK); + + /* + * See APM section 15.36.11 on how to handle the RMP fault for the large pages. + * + * npt rmp access action + * -------------------------------------------------- + * 4k 2M C=1 psmash + * x x C=1 if page is not private then add a new RMP entry + * x x C=0 if page is private then make it shared + * 2M 4k C=x zap + */ + if ((error_code & PFERR_GUEST_SIZEM_MASK) || + ((level == PG_LEVEL_4K) && (rlevel == PG_LEVEL_2M) && private)) { + rc = snp_rmptable_psmash(vcpu, pfn); + goto zap_gfn; + } + + /* + * If it's a private access, and the page is not assigned in the RMP table, create a + * new private RMP entry. + */ + if (!rmpentry_assigned(e) && private) { + rc = snp_make_page_private(vcpu, gpa, pfn, PG_LEVEL_4K); + goto zap_gfn; + } + + /* + * If it's a shared access, then make the page shared in the RMP table. + */ + if (rmpentry_assigned(e) && !private) + rc = snp_make_page_shared(vcpu, gpa, pfn, PG_LEVEL_4K); + +zap_gfn: + /* + * Now that we have updated the RMP pagesize, zap the existing rmaps for + * large entry ranges so that nested page table gets rebuilt with the updated RMP + * pagesize. + */ + gfn = gpa_to_gfn(gpa) & ~(KVM_PAGES_PER_HPAGE(PG_LEVEL_2M) - 1); + kvm_zap_gfn_range(vcpu->kvm, gfn, gfn + 512); + + return 0; +} diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 4ff6fc86dd18..32e35d396508 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4579,6 +4579,8 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { .get_tdp_max_page_level = sev_get_tdp_max_page_level, .write_page_begin = sev_snp_write_page_begin, + + .handle_rmp_page_fault = snp_handle_rmp_page_fault, }; static struct kvm_x86_init_ops svm_init_ops __initdata = { diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index e0276ad8a1ae..ccdaaa4e1fb1 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -577,6 +577,8 @@ void sev_es_unmap_ghcb(struct vcpu_svm *svm); struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu); int sev_get_tdp_max_page_level(struct kvm_vcpu *vcpu, gpa_t gpa, int max_level); void sev_snp_write_page_begin(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn); +int snp_handle_rmp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, kvm_pfn_t pfn, + int level, u64 error_code); /* vmenter.S */ -- 2.17.1