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Date: Mon, 9 Nov 2020 16:25:31 -0600
From: Tom Lendacky <thomas.lendacky@....com>
To: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>,
Sean Christopherson <sean.j.christopherson@...el.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Borislav Petkov <bp@...en8.de>, Ingo Molnar <mingo@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH v3 05/34] KVM: SVM: Add support for the SEV-ES VMSA
From: Tom Lendacky <thomas.lendacky@....com>
Allocate a page during vCPU creation to be used as the encrypted VM save
area (VMSA) for the SEV-ES guest. Provide a flag in the kvm_vcpu_arch
structure that indicates whether the guest state is protected.
When freeing a VMSA page that has been encrypted, the cache contents must
be flushed using the MSR_AMD64_VM_PAGE_FLUSH before freeing the page.
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
arch/x86/include/asm/kvm_host.h | 3 ++
arch/x86/kvm/svm/sev.c | 64 +++++++++++++++++++++++++++++++++
arch/x86/kvm/svm/svm.c | 24 +++++++++++--
arch/x86/kvm/svm/svm.h | 5 +++
4 files changed, 94 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index d44858b69353..7776bb18e29d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -804,6 +804,9 @@ struct kvm_vcpu_arch {
*/
bool enforce;
} pv_cpuid;
+
+ /* Protected Guests */
+ bool guest_state_protected;
};
struct kvm_lpage_info {
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 9bf5e9dadff5..151e9eab85a9 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -14,6 +14,7 @@
#include <linux/psp-sev.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
+#include <asm/processor.h>
#include "x86.h"
#include "svm.h"
@@ -1190,6 +1191,69 @@ void sev_hardware_teardown(void)
sev_flush_asids();
}
+/*
+ * Pages used by hardware to hold guest encrypted state must be flushed before
+ * returning them to the system.
+ */
+void sev_flush_guest_memory(struct vcpu_svm *svm, void *va, unsigned long len)
+{
+ /*
+ * If hardware enforced cache coherency for encrypted mappings of the
+ * same physical page is supported, nothing to do.
+ */
+ if (boot_cpu_has(X86_FEATURE_SME_COHERENT))
+ return;
+
+ /*
+ * If the VM Page Flush MSR is supported, use it to flush the page
+ * (using the page virtual address and the guest ASID).
+ */
+ if (boot_cpu_has(X86_FEATURE_VM_PAGE_FLUSH)) {
+ struct kvm_sev_info *sev;
+ u64 start, stop;
+
+ /* Align start and stop to page boundaries. */
+ start = (u64)va & PAGE_MASK;
+ stop = PAGE_ALIGN((u64)va + len);
+
+ if (start < stop) {
+ sev = &to_kvm_svm(svm->vcpu.kvm)->sev_info;
+
+ while (start < stop) {
+ wrmsrl(MSR_AMD64_VM_PAGE_FLUSH,
+ start | sev->asid);
+
+ start += PAGE_SIZE;
+ }
+
+ return;
+ } else {
+ WARN(1, "Address overflow, using WBINVD\n");
+ }
+ }
+
+ /*
+ * Hardware should always have one of the above features,
+ * but if not, use WBINVD and issue a warning.
+ */
+ WARN_ONCE(1, "Using WBINVD to flush guest memory\n");
+ wbinvd_on_all_cpus();
+}
+
+void sev_free_vcpu(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_svm *svm;
+
+ if (!sev_es_guest(vcpu->kvm))
+ return;
+
+ svm = to_svm(vcpu);
+
+ if (vcpu->arch.guest_state_protected)
+ sev_flush_guest_memory(svm, svm->vmsa, PAGE_SIZE);
+ __free_page(virt_to_page(svm->vmsa));
+}
+
void pre_sev_run(struct vcpu_svm *svm, int cpu)
{
struct svm_cpu_data *sd = per_cpu(svm_data, cpu);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index a3198b65f431..d45b2dc5cabe 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1288,6 +1288,7 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm;
struct page *vmcb_page;
+ struct page *vmsa_page = NULL;
int err;
BUILD_BUG_ON(offsetof(struct vcpu_svm, vcpu) != 0);
@@ -1298,9 +1299,19 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
if (!vmcb_page)
goto out;
+ if (sev_es_guest(svm->vcpu.kvm)) {
+ /*
+ * SEV-ES guests require a separate VMSA page used to contain
+ * the encrypted register state of the guest.
+ */
+ vmsa_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+ if (!vmsa_page)
+ goto error_free_vmcb_page;
+ }
+
err = avic_init_vcpu(svm);
if (err)
- goto error_free_vmcb_page;
+ goto error_free_vmsa_page;
/* We initialize this flag to true to make sure that the is_running
* bit would be set the first time the vcpu is loaded.
@@ -1310,12 +1321,16 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
svm->msrpm = svm_vcpu_alloc_msrpm();
if (!svm->msrpm)
- goto error_free_vmcb_page;
+ goto error_free_vmsa_page;
svm_vcpu_init_msrpm(vcpu, svm->msrpm);
svm->vmcb = page_address(vmcb_page);
svm->vmcb_pa = __sme_set(page_to_pfn(vmcb_page) << PAGE_SHIFT);
+
+ if (vmsa_page)
+ svm->vmsa = page_address(vmsa_page);
+
svm->asid_generation = 0;
init_vmcb(svm);
@@ -1324,6 +1339,9 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
return 0;
+error_free_vmsa_page:
+ if (vmsa_page)
+ __free_page(vmsa_page);
error_free_vmcb_page:
__free_page(vmcb_page);
out:
@@ -1351,6 +1369,8 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu)
svm_free_nested(svm);
+ sev_free_vcpu(vcpu);
+
__free_page(pfn_to_page(__sme_clr(svm->vmcb_pa) >> PAGE_SHIFT));
__free_pages(virt_to_page(svm->msrpm), MSRPM_ALLOC_ORDER);
}
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index af9e5910817c..8f0a3ed0d790 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -167,6 +167,10 @@ struct vcpu_svm {
DECLARE_BITMAP(read, MAX_DIRECT_ACCESS_MSRS);
DECLARE_BITMAP(write, MAX_DIRECT_ACCESS_MSRS);
} shadow_msr_intercept;
+
+ /* SEV-ES support */
+ struct vmcb_save_area *vmsa;
+ struct ghcb *ghcb;
};
struct svm_cpu_data {
@@ -512,5 +516,6 @@ int svm_unregister_enc_region(struct kvm *kvm,
void pre_sev_run(struct vcpu_svm *svm, int cpu);
void __init sev_hardware_setup(void);
void sev_hardware_teardown(void);
+void sev_free_vcpu(struct kvm_vcpu *vcpu);
#endif
--
2.28.0
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