| Message ID | 20231230172351.574091-29-michael.roth@amd.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support | expand |
On 12/31/2023 1:23 AM, Michael Roth wrote: > This will handle RMP table updates and direct map changes needed to put > a page into a private state before mapping it into an SEV-SNP guest. > > Signed-off-by: Michael Roth <michael.roth@amd.com> > --- > arch/x86/kvm/Kconfig | 1 + > arch/x86/kvm/svm/sev.c | 98 ++++++++++++++++++++++++++++++++++++++++++ > arch/x86/kvm/svm/svm.c | 2 + > arch/x86/kvm/svm/svm.h | 1 + > virt/kvm/guest_memfd.c | 4 +- > 5 files changed, 104 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig > index 4ec53d6d5773..79c002e1bb5c 100644 > --- a/arch/x86/kvm/Kconfig > +++ b/arch/x86/kvm/Kconfig > @@ -125,6 +125,7 @@ config KVM_AMD_SEV > depends on KVM_AMD && X86_64 > depends on CRYPTO_DEV_SP_PSP && !(KVM_AMD=y && CRYPTO_DEV_CCP_DD=m) > select KVM_GENERIC_PRIVATE_MEM > + select HAVE_KVM_GMEM_PREPARE > help > Provides support for launching Encrypted VMs (SEV) and Encrypted VMs > with Encrypted State (SEV-ES) on AMD processors. > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index b2ac696c436a..91f53f4a6059 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -4154,3 +4154,101 @@ void handle_rmp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code) > out: > put_page(pfn_to_page(pfn)); > } > + > +static bool is_pfn_range_shared(kvm_pfn_t start, kvm_pfn_t end) > +{ > + kvm_pfn_t pfn = start; > + > + while (pfn < end) { > + int ret, rmp_level; > + bool assigned; > + > + ret = snp_lookup_rmpentry(pfn, &assigned, &rmp_level); > + if (ret) { > + pr_warn_ratelimited("SEV: Failed to retrieve RMP entry: PFN 0x%llx GFN start 0x%llx GFN end 0x%llx RMP level %d error %d\n", > + pfn, start, end, rmp_level, ret); > + return false; > + } > + > + if (assigned) { > + pr_debug("%s: overlap detected, PFN 0x%llx start 0x%llx end 0x%llx RMP level %d\n", > + __func__, pfn, start, end, rmp_level); > + return false; > + } > + > + pfn++; rmp_level can be got from snp_lookup_rmpentry(). I think the pfn can be updated according to rmp_level to avoid unnecessary loops for 2MB large page, right? > + } > + > + return true; > +} > + > +static u8 max_level_for_order(int order) > +{ > + if (order >= KVM_HPAGE_GFN_SHIFT(PG_LEVEL_2M)) > + return PG_LEVEL_2M; > + > + return PG_LEVEL_4K; > +} > + > +static bool is_large_rmp_possible(struct kvm *kvm, kvm_pfn_t pfn, int order) > +{ > + kvm_pfn_t pfn_aligned = ALIGN_DOWN(pfn, PTRS_PER_PMD); > + > + /* > + * If this is a large folio, and the entire 2M range containing the > + * PFN is currently shared, then the entire 2M-aligned range can be > + * set to private via a single 2M RMP entry. > + */ > + if (max_level_for_order(order) > PG_LEVEL_4K && > + is_pfn_range_shared(pfn_aligned, pfn_aligned + PTRS_PER_PMD)) > + return true; > + > + return false; > +} > + > +int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order) > +{ > + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > + kvm_pfn_t pfn_aligned; > + gfn_t gfn_aligned; > + int level, rc; > + bool assigned; > + > + if (!sev_snp_guest(kvm)) > + return 0; > + > + rc = snp_lookup_rmpentry(pfn, &assigned, &level); > + if (rc) { > + pr_err_ratelimited("SEV: Failed to look up RMP entry: GFN %llx PFN %llx error %d\n", > + gfn, pfn, rc); > + return -ENOENT; > + } > + > + if (assigned) { > + pr_debug("%s: already assigned: gfn %llx pfn %llx max_order %d level %d\n", > + __func__, gfn, pfn, max_order, level); > + return 0; > + } > + > + if (is_large_rmp_possible(kvm, pfn, max_order)) { > + level = PG_LEVEL_2M; > + pfn_aligned = ALIGN_DOWN(pfn, PTRS_PER_PMD); > + gfn_aligned = ALIGN_DOWN(gfn, PTRS_PER_PMD); > + } else { > + level = PG_LEVEL_4K; > + pfn_aligned = pfn; > + gfn_aligned = gfn; > + } > + > + rc = rmp_make_private(pfn_aligned, gfn_to_gpa(gfn_aligned), level, sev->asid, false); > + if (rc) { > + pr_err_ratelimited("SEV: Failed to update RMP entry: GFN %llx PFN %llx level %d error %d\n", > + gfn, pfn, level, rc); > + return -EINVAL; > + } > + > + pr_debug("%s: updated: gfn %llx pfn %llx pfn_aligned %llx max_order %d level %d\n", > + __func__, gfn, pfn, pfn_aligned, max_order, level); > + > + return 0; > +} > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index 240518f8d6c7..32cef8626b57 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -5065,6 +5065,8 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { > .vcpu_deliver_sipi_vector = svm_vcpu_deliver_sipi_vector, > .vcpu_get_apicv_inhibit_reasons = avic_vcpu_get_apicv_inhibit_reasons, > .alloc_apic_backing_page = svm_alloc_apic_backing_page, > + > + .gmem_prepare = sev_gmem_prepare, > }; > > /* > diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h > index d953ae41c619..9ece9612dbb9 100644 > --- a/arch/x86/kvm/svm/svm.h > +++ b/arch/x86/kvm/svm/svm.h > @@ -725,6 +725,7 @@ void sev_es_unmap_ghcb(struct vcpu_svm *svm); > struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu); > void handle_rmp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code); > void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu); > +int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order); > > /* vmenter.S */ > > diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c > index feec0da93d98..ddea45279fef 100644 > --- a/virt/kvm/guest_memfd.c > +++ b/virt/kvm/guest_memfd.c > @@ -66,8 +66,8 @@ static int kvm_gmem_prepare_folio(struct inode *inode, pgoff_t index, struct fol > gfn = slot->base_gfn + index - slot->gmem.pgoff; > rc = kvm_arch_gmem_prepare(kvm, gfn, pfn, compound_order(compound_head(page))); > if (rc) { > - pr_warn_ratelimited("gmem: Failed to prepare folio for index %lx, error %d.\n", > - index, rc); > + pr_warn_ratelimited("gmem: Failed to prepare folio for index %lx GFN %llx PFN %llx error %d.\n", > + index, gfn, pfn, rc); > return rc; > } > }
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig index 4ec53d6d5773..79c002e1bb5c 100644 --- a/arch/x86/kvm/Kconfig +++ b/arch/x86/kvm/Kconfig @@ -125,6 +125,7 @@ config KVM_AMD_SEV depends on KVM_AMD && X86_64 depends on CRYPTO_DEV_SP_PSP && !(KVM_AMD=y && CRYPTO_DEV_CCP_DD=m) select KVM_GENERIC_PRIVATE_MEM + select HAVE_KVM_GMEM_PREPARE help Provides support for launching Encrypted VMs (SEV) and Encrypted VMs with Encrypted State (SEV-ES) on AMD processors. diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index b2ac696c436a..91f53f4a6059 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -4154,3 +4154,101 @@ void handle_rmp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code) out: put_page(pfn_to_page(pfn)); } + +static bool is_pfn_range_shared(kvm_pfn_t start, kvm_pfn_t end) +{ + kvm_pfn_t pfn = start; + + while (pfn < end) { + int ret, rmp_level; + bool assigned; + + ret = snp_lookup_rmpentry(pfn, &assigned, &rmp_level); + if (ret) { + pr_warn_ratelimited("SEV: Failed to retrieve RMP entry: PFN 0x%llx GFN start 0x%llx GFN end 0x%llx RMP level %d error %d\n", + pfn, start, end, rmp_level, ret); + return false; + } + + if (assigned) { + pr_debug("%s: overlap detected, PFN 0x%llx start 0x%llx end 0x%llx RMP level %d\n", + __func__, pfn, start, end, rmp_level); + return false; + } + + pfn++; + } + + return true; +} + +static u8 max_level_for_order(int order) +{ + if (order >= KVM_HPAGE_GFN_SHIFT(PG_LEVEL_2M)) + return PG_LEVEL_2M; + + return PG_LEVEL_4K; +} + +static bool is_large_rmp_possible(struct kvm *kvm, kvm_pfn_t pfn, int order) +{ + kvm_pfn_t pfn_aligned = ALIGN_DOWN(pfn, PTRS_PER_PMD); + + /* + * If this is a large folio, and the entire 2M range containing the + * PFN is currently shared, then the entire 2M-aligned range can be + * set to private via a single 2M RMP entry. + */ + if (max_level_for_order(order) > PG_LEVEL_4K && + is_pfn_range_shared(pfn_aligned, pfn_aligned + PTRS_PER_PMD)) + return true; + + return false; +} + +int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order) +{ + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; + kvm_pfn_t pfn_aligned; + gfn_t gfn_aligned; + int level, rc; + bool assigned; + + if (!sev_snp_guest(kvm)) + return 0; + + rc = snp_lookup_rmpentry(pfn, &assigned, &level); + if (rc) { + pr_err_ratelimited("SEV: Failed to look up RMP entry: GFN %llx PFN %llx error %d\n", + gfn, pfn, rc); + return -ENOENT; + } + + if (assigned) { + pr_debug("%s: already assigned: gfn %llx pfn %llx max_order %d level %d\n", + __func__, gfn, pfn, max_order, level); + return 0; + } + + if (is_large_rmp_possible(kvm, pfn, max_order)) { + level = PG_LEVEL_2M; + pfn_aligned = ALIGN_DOWN(pfn, PTRS_PER_PMD); + gfn_aligned = ALIGN_DOWN(gfn, PTRS_PER_PMD); + } else { + level = PG_LEVEL_4K; + pfn_aligned = pfn; + gfn_aligned = gfn; + } + + rc = rmp_make_private(pfn_aligned, gfn_to_gpa(gfn_aligned), level, sev->asid, false); + if (rc) { + pr_err_ratelimited("SEV: Failed to update RMP entry: GFN %llx PFN %llx level %d error %d\n", + gfn, pfn, level, rc); + return -EINVAL; + } + + pr_debug("%s: updated: gfn %llx pfn %llx pfn_aligned %llx max_order %d level %d\n", + __func__, gfn, pfn, pfn_aligned, max_order, level); + + return 0; +} diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 240518f8d6c7..32cef8626b57 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -5065,6 +5065,8 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { .vcpu_deliver_sipi_vector = svm_vcpu_deliver_sipi_vector, .vcpu_get_apicv_inhibit_reasons = avic_vcpu_get_apicv_inhibit_reasons, .alloc_apic_backing_page = svm_alloc_apic_backing_page, + + .gmem_prepare = sev_gmem_prepare, }; /* diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index d953ae41c619..9ece9612dbb9 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -725,6 +725,7 @@ void sev_es_unmap_ghcb(struct vcpu_svm *svm); struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu); void handle_rmp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code); void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu); +int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order); /* vmenter.S */ diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index feec0da93d98..ddea45279fef 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -66,8 +66,8 @@ static int kvm_gmem_prepare_folio(struct inode *inode, pgoff_t index, struct fol gfn = slot->base_gfn + index - slot->gmem.pgoff; rc = kvm_arch_gmem_prepare(kvm, gfn, pfn, compound_order(compound_head(page))); if (rc) { - pr_warn_ratelimited("gmem: Failed to prepare folio for index %lx, error %d.\n", - index, rc); + pr_warn_ratelimited("gmem: Failed to prepare folio for index %lx GFN %llx PFN %llx error %d.\n", + index, gfn, pfn, rc); return rc; } }
This will handle RMP table updates and direct map changes needed to put a page into a private state before mapping it into an SEV-SNP guest. Signed-off-by: Michael Roth <michael.roth@amd.com> --- arch/x86/kvm/Kconfig | 1 + arch/x86/kvm/svm/sev.c | 98 ++++++++++++++++++++++++++++++++++++++++++ arch/x86/kvm/svm/svm.c | 2 + arch/x86/kvm/svm/svm.h | 1 + virt/kvm/guest_memfd.c | 4 +- 5 files changed, 104 insertions(+), 2 deletions(-)