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Message-ID: <20231016132819.1002933-40-michael.roth@amd.com>
Date: Mon, 16 Oct 2023 08:28:08 -0500
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>, <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>, <jarkko@...nel.org>, <ashish.kalra@....com>,
<nikunj.dadhania@....com>, <pankaj.gupta@....com>,
<liam.merwick@...cle.com>, <zhi.a.wang@...el.com>
Subject: [PATCH v10 39/50] KVM: SEV: Implement gmem hook for initializing private pages
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@....com>
---
arch/x86/kvm/Kconfig | 1 +
arch/x86/kvm/svm/sev.c | 95 ++++++++++++++++++++++++++++++++++++++++++
arch/x86/kvm/svm/svm.c | 2 +
arch/x86/kvm/svm/svm.h | 1 +
4 files changed, 99 insertions(+)
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 71dc506aa3fb..8caf2eb6add8 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -127,6 +127,7 @@ 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_SW_PROTECTED_VM
+ 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 9c38fe796e00..8cf2d19597b1 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -4135,3 +4135,98 @@ 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)
+ return rc;
+
+ 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 f5cdcbd1ba67..b3ed424533b0 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -5041,6 +5041,8 @@ 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 f81dfa1594f6..c5cee554176e 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -723,6 +723,7 @@ 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 */
--
2.25.1
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