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Date: Wed, 14 Dec 2022 13:40:33 -0600
From: Michael Roth <michael.roth@....com>
To: <kvm@...r.kernel.org>
CC: <linux-coco@...ts.linux.dev>, <linux-mm@...ck.org>,
<linux-crypto@...r.kernel.org>, <x86@...nel.org>,
<linux-kernel@...r.kernel.org>, <tglx@...utronix.de>,
<mingo@...hat.com>, <jroedel@...e.de>, <thomas.lendacky@....com>,
<hpa@...or.com>, <ardb@...nel.org>, <pbonzini@...hat.com>,
<seanjc@...gle.com>, <vkuznets@...hat.com>,
<wanpengli@...cent.com>, <jmattson@...gle.com>, <luto@...nel.org>,
<dave.hansen@...ux.intel.com>, <slp@...hat.com>,
<pgonda@...gle.com>, <peterz@...radead.org>,
<srinivas.pandruvada@...ux.intel.com>, <rientjes@...gle.com>,
<dovmurik@...ux.ibm.com>, <tobin@....com>, <bp@...en8.de>,
<vbabka@...e.cz>, <kirill@...temov.name>, <ak@...ux.intel.com>,
<tony.luck@...el.com>, <marcorr@...gle.com>,
<sathyanarayanan.kuppuswamy@...ux.intel.com>,
<alpergun@...gle.com>, <dgilbert@...hat.com>, <jarkko@...nel.org>,
<ashish.kalra@....com>, <harald@...fian.com>,
Brijesh Singh <brijesh.singh@....com>,
Jarkko Sakkinen <jarkko@...fian.com>,
Ashish Kalra <Ashish.Kalra@....com>
Subject: [PATCH RFC v7 41/64] KVM: X86: Keep the NPT and RMP page level in sync
From: Brijesh Singh <brijesh.singh@....com>
When running an SEV-SNP VM, the sPA used to index the RMP entry is
obtained through the NPT translation (gva->gpa->spa). The NPT page
level is checked against the page level programmed in the RMP entry.
If the page level does not match, then it will cause a nested page
fault with the RMP bit set to indicate the RMP violation.
Co-developed-by: Michael Roth <michael.roth@....com>
Signed-off-by: Michael Roth <michael.roth@....com>
Signed-off-by: Brijesh Singh <brijesh.singh@....com>
Signed-off-by: Jarkko Sakkinen <jarkko@...fian.com>
Signed-off-by: Ashish Kalra <Ashish.Kalra@....com>
---
arch/x86/include/asm/kvm-x86-ops.h | 1 +
arch/x86/include/asm/kvm_host.h | 2 +
arch/x86/kvm/mmu/mmu.c | 12 +++++-
arch/x86/kvm/svm/sev.c | 66 ++++++++++++++++++++++++++++++
arch/x86/kvm/svm/svm.c | 2 +
arch/x86/kvm/svm/svm.h | 1 +
6 files changed, 83 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index e0015926cdf4..61e31b622fce 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -136,6 +136,7 @@ KVM_X86_OP_OPTIONAL_RET0(private_mem_enabled);
KVM_X86_OP_OPTIONAL_RET0(fault_is_private);
KVM_X86_OP_OPTIONAL_RET0(update_mem_attr)
KVM_X86_OP_OPTIONAL(invalidate_restricted_mem)
+KVM_X86_OP_OPTIONAL(rmp_page_level_adjust)
#undef KVM_X86_OP
#undef KVM_X86_OP_OPTIONAL
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index e2529415f28b..b126c6ac7ce4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1724,6 +1724,8 @@ struct kvm_x86_ops {
unsigned long (*vcpu_get_apicv_inhibit_reasons)(struct kvm_vcpu *vcpu);
void *(*alloc_apic_backing_page)(struct kvm_vcpu *vcpu);
+
+ void (*rmp_page_level_adjust)(struct kvm *kvm, gfn_t gfn, int *level);
};
struct kvm_x86_nested_ops {
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 2713632e5061..25db83021500 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3053,6 +3053,11 @@ static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn,
out:
local_irq_restore(flags);
+
+ /* Adjust the page level based on the SEV-SNP RMP page level. */
+ if (kvm_x86_ops.rmp_page_level_adjust)
+ static_call(kvm_x86_rmp_page_level_adjust)(kvm, gfn, &level);
+
return level;
}
@@ -3070,8 +3075,13 @@ int kvm_mmu_max_mapping_level(struct kvm *kvm,
break;
}
- if (is_private)
+ pr_debug("%s: gfn: %llx max_level: %d max_huge_page_level: %d\n",
+ __func__, gfn, max_level, max_huge_page_level);
+ if (kvm_slot_can_be_private(slot) && is_private) {
+ if (kvm_x86_ops.rmp_page_level_adjust)
+ static_call(kvm_x86_rmp_page_level_adjust)(kvm, gfn, &max_level);
return max_level;
+ }
if (max_level == PG_LEVEL_4K)
return PG_LEVEL_4K;
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 6f901545bed9..443c5c8aaaf3 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3710,6 +3710,72 @@ struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu)
return p;
}
+static bool is_pfn_range_shared(kvm_pfn_t start, kvm_pfn_t end)
+{
+ int level;
+
+ while (end > start) {
+ if (snp_lookup_rmpentry(start, &level) != 0)
+ return false;
+ start++;
+ }
+
+ return true;
+}
+
+void sev_rmp_page_level_adjust(struct kvm *kvm, gfn_t gfn, int *level)
+{
+ struct kvm_memory_slot *slot;
+ int ret, order, assigned;
+ int rmp_level = 1;
+ kvm_pfn_t pfn;
+
+ slot = gfn_to_memslot(kvm, gfn);
+ if (!kvm_slot_can_be_private(slot))
+ return;
+
+ ret = kvm_restricted_mem_get_pfn(slot, gfn, &pfn, &order);
+ if (ret) {
+ pr_warn_ratelimited("Failed to adjust RMP page level, unable to obtain private PFN, rc: %d\n",
+ ret);
+ *level = PG_LEVEL_4K;
+ return;
+ }
+
+ /* If there's an error retrieving RMP entry, stick with 4K mappings */
+ assigned = snp_lookup_rmpentry(pfn, &rmp_level);
+ if (unlikely(assigned < 0))
+ goto out_adjust;
+
+ if (!assigned) {
+ kvm_pfn_t huge_pfn;
+
+ /*
+ * If all the pages are shared then no need to keep the RMP
+ * and NPT in sync.
+ */
+ huge_pfn = pfn & ~(PTRS_PER_PMD - 1);
+ if (is_pfn_range_shared(huge_pfn, huge_pfn + PTRS_PER_PMD))
+ goto out;
+ }
+
+ /*
+ * The hardware installs 2MB TLB entries to access to 1GB pages,
+ * therefore allow NPT to use 1GB pages when pfn was added as 2MB
+ * in the RMP table.
+ */
+ if (rmp_level == PG_LEVEL_2M && (*level == PG_LEVEL_1G))
+ goto out;
+
+out_adjust:
+ /* Adjust the level to keep the NPT and RMP in sync */
+ *level = min_t(size_t, *level, rmp_level);
+out:
+ put_page(pfn_to_page(pfn));
+ pr_debug("%s: GFN: 0x%llx, level: %d, rmp_level: %d, ret: %d\n",
+ __func__, gfn, *level, rmp_level, ret);
+}
+
int sev_fault_is_private(struct kvm *kvm, gpa_t gpa, u64 error_code, bool *private_fault)
{
gfn_t gfn = gpa_to_gfn(gpa);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 013f811c733c..2dfa150bcb09 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4843,6 +4843,8 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
.alloc_apic_backing_page = svm_alloc_apic_backing_page,
.fault_is_private = sev_fault_is_private,
+
+ .rmp_page_level_adjust = sev_rmp_page_level_adjust,
};
/*
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 17200c1ad20e..ae733188cf87 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -698,6 +698,7 @@ void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector);
void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa);
void sev_es_unmap_ghcb(struct vcpu_svm *svm);
struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu);
+void sev_rmp_page_level_adjust(struct kvm *kvm, gfn_t gfn, int *level);
int sev_fault_is_private(struct kvm *kvm, gpa_t gpa, u64 error_code, bool *private_fault);
--
2.25.1
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