[PATCH v9 02/43] KVM: SVM: Create a separate mapping for the SEV-ES save area

Brijesh Singh
2022-01-28T17:18:34Z

From: Tom Lendacky <thomas.lendacky@amd.com>

The save area for SEV-ES/SEV-SNP guests, as used by the hardware, is
different from the save area of a non SEV-ES/SEV-SNP guest.

This is the first step in defining the multiple save areas to keep them
separate and ensuring proper operation amongst the different types of
guests. Create an SEV-ES/SEV-SNP save area and adjust usage to the new
save area definition where needed.

Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
arch/x86/include/asm/svm.h | 87 +++++++++++++++++++++++++++++---------
arch/x86/kvm/svm/sev.c | 24 +++++------
arch/x86/kvm/svm/svm.h | 2 +-
3 files changed, 80 insertions(+), 33 deletions(-)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 7c9cf4f3c164..3ce2e575a2de 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -227,6 +227,7 @@ struct vmcb_seg {
u64 base;
} __packed;

+/* Save area definition for legacy and SEV-MEM guests */
struct vmcb_save_area {
struct vmcb_seg es;
struct vmcb_seg cs;
@@ -243,8 +244,58 @@ struct vmcb_save_area {
u8 cpl;
u8 reserved_2[4];
u64 efer;
+ u8 reserved_3[112];
+ u64 cr4;
+ u64 cr3;
+ u64 cr0;
+ u64 dr7;
+ u64 dr6;
+ u64 rflags;
+ u64 rip;
+ u8 reserved_4[88];
+ u64 rsp;
+ u64 s_cet;
+ u64 ssp;
+ u64 isst_addr;
+ u64 rax;
+ u64 star;
+ u64 lstar;
+ u64 cstar;
+ u64 sfmask;
+ u64 kernel_gs_base;
+ u64 sysenter_cs;
+ u64 sysenter_esp;
+ u64 sysenter_eip;
+ u64 cr2;
+ u8 reserved_5[32];
+ u64 g_pat;
+ u64 dbgctl;
+ u64 br_from;
+ u64 br_to;
+ u64 last_excp_from;
+ u64 last_excp_to;
+ u8 reserved_6[72];
+ u32 spec_ctrl; /* Guest version of SPEC_CTRL at 0x2E0 */
+} __packed;
+
+/* Save area definition for SEV-ES and SEV-SNP guests */
+struct sev_es_save_area {
+ struct vmcb_seg es;
+ struct vmcb_seg cs;
+ struct vmcb_seg ss;
+ struct vmcb_seg ds;
+ struct vmcb_seg fs;
+ struct vmcb_seg gs;
+ struct vmcb_seg gdtr;
+ struct vmcb_seg ldtr;
+ struct vmcb_seg idtr;
+ struct vmcb_seg tr;
+ u8 reserved_1[43];
+ u8 cpl;
+ u8 reserved_2[4];
+ u64 efer;
u8 reserved_3[104];
- u64 xss; /* Valid for SEV-ES only */
+ u64 xss;
u64 cr4;
u64 cr3;
u64 cr0;
@@ -272,22 +323,14 @@ struct vmcb_save_area {
u64 br_to;
u64 last_excp_from;
u64 last_excp_to;
-
- /*
- * The following part of the save area is valid only for
- * SEV-ES guests when referenced through the GHCB or for
- * saving to the host save area.
- */
- u8 reserved_7[72];
- u32 spec_ctrl; /* Guest version of SPEC_CTRL at 0x2E0 */
- u8 reserved_7b[4];
+ u8 reserved_7[80];
u32 pkru;
- u8 reserved_7a[20];
- u64 reserved_8; /* rax already available at 0x01f8 */
+ u8 reserved_9[20];
+ u64 reserved_10; /* rax already available at 0x01f8 */
u64 rcx;
u64 rdx;
u64 rbx;
- u64 reserved_9; /* rsp already available at 0x01d8 */
+ u64 reserved_11; /* rsp already available at 0x01d8 */
u64 rbp;
u64 rsi;
u64 rdi;
@@ -299,23 +342,25 @@ struct vmcb_save_area {
u64 r13;
u64 r14;
u64 r15;
- u8 reserved_10[16];
+ u8 reserved_12[16];
u64 sw_exit_code;
u64 sw_exit_info_1;
u64 sw_exit_info_2;
u64 sw_scratch;
u64 sev_features;
- u8 reserved_11[48];
+ u8 reserved_13[48];
u64 xcr0;
u8 valid_bitmap[16];
u64 x87_state_gpa;
} __packed;

+#define GHCB_SHARED_BUF_SIZE 2032
+
struct ghcb {
- struct vmcb_save_area save;
- u8 reserved_save[2048 - sizeof(struct vmcb_save_area)];
+ struct sev_es_save_area save;
+ u8 reserved_save[2048 - sizeof(struct sev_es_save_area)];

- u8 shared_buffer[2032];
+ u8 shared_buffer[GHCB_SHARED_BUF_SIZE];

u8 reserved_1[10];
u16 protocol_version; /* negotiated SEV-ES/GHCB protocol version */
@@ -323,13 +368,15 @@ struct ghcb {
} __packed;

-#define EXPECTED_VMCB_SAVE_AREA_SIZE 1032
+#define EXPECTED_VMCB_SAVE_AREA_SIZE 740
+#define EXPECTED_SEV_ES_SAVE_AREA_SIZE 1032
#define EXPECTED_VMCB_CONTROL_AREA_SIZE 1024
#define EXPECTED_GHCB_SIZE PAGE_SIZE

static inline void __unused_size_checks(void)
{
BUILD_BUG_ON(sizeof(struct vmcb_save_area) != EXPECTED_VMCB_SAVE_AREA_SIZE);
+ BUILD_BUG_ON(sizeof(struct sev_es_save_area) != EXPECTED_SEV_ES_SAVE_AREA_SIZE);
BUILD_BUG_ON(sizeof(struct vmcb_control_area) != EXPECTED_VMCB_CONTROL_AREA_SIZE);
BUILD_BUG_ON(sizeof(struct ghcb) != EXPECTED_GHCB_SIZE);
}
@@ -399,7 +446,7 @@ struct vmcb {
/* GHCB Accessor functions */

#define GHCB_BITMAP_IDX(field) \
- (offsetof(struct vmcb_save_area, field) / sizeof(u64))
+ (offsetof(struct sev_es_save_area, field) / sizeof(u64))

#define DEFINE_GHCB_ACCESSORS(field) \
static inline bool ghcb_##field##_is_valid(const struct ghcb *ghcb) \
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 6a22798eaaee..44bad375b4d6 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -558,12 +558,20 @@ static int sev_launch_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)

static int sev_es_sync_vmsa(struct vcpu_svm *svm)
{
- struct vmcb_save_area *save = &svm->vmcb->save;
+ struct sev_es_save_area *save = svm->sev_es.vmsa;

/* Check some debug related fields before encrypting the VMSA */
- if (svm->vcpu.guest_debug || (save->dr7 & ~DR7_FIXED_1))
+ if (svm->vcpu.guest_debug || (svm->vmcb->save.dr7 & ~DR7_FIXED_1))
return -EINVAL;

+ /*
+ * SEV-ES will use a VMSA that is pointed to by the VMCB, not
+ * the traditional VMSA that is part of the VMCB. Copy the
+ * traditional VMSA as it has been built so far (in prep
+ * for LAUNCH_UPDATE_VMSA) to be the initial SEV-ES state.
+ */
+ memcpy(save, &svm->vmcb->save, sizeof(svm->vmcb->save));
+
/* Sync registgers */
save->rax = svm->vcpu.arch.regs[VCPU_REGS_RAX];
save->rbx = svm->vcpu.arch.regs[VCPU_REGS_RBX];
@@ -591,14 +599,6 @@ static int sev_es_sync_vmsa(struct vcpu_svm *svm)
save->xss = svm->vcpu.arch.ia32_xss;
save->dr6 = svm->vcpu.arch.dr6;

- /*
- * SEV-ES will use a VMSA that is pointed to by the VMCB, not
- * the traditional VMSA that is part of the VMCB. Copy the
- * traditional VMSA as it has been built so far (in prep
- * for LAUNCH_UPDATE_VMSA) to be the initial SEV-ES state.
- */
- memcpy(svm->sev_es.vmsa, save, sizeof(*save));
-
return 0;
}

@@ -2905,7 +2905,7 @@ void sev_es_vcpu_reset(struct vcpu_svm *svm)
void sev_es_prepare_guest_switch(struct vcpu_svm *svm, unsigned int cpu)
{
struct svm_cpu_data *sd = per_cpu(svm_data, cpu);
- struct vmcb_save_area *hostsa;
+ struct sev_es_save_area *hostsa;

/*
* As an SEV-ES guest, hardware will restore the host state on VMEXIT,
@@ -2915,7 +2915,7 @@ void sev_es_prepare_guest_switch(struct vcpu_svm *svm, unsigned int cpu)
vmsave(__sme_page_pa(sd->save_area));

/* XCR0 is restored on VMEXIT, save the current host value */
- hostsa = (struct vmcb_save_area *)(page_address(sd->save_area) + 0x400);
+ hostsa = (struct sev_es_save_area *)(page_address(sd->save_area) + 0x400);
hostsa->xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);

/* PKRU is restored on VMEXIT, save the current host value */
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 47ef8f4a9358..9597331e9a32 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -167,7 +167,7 @@ struct svm_nested_state {

struct vcpu_sev_es_state {
/* SEV-ES support */
- struct vmcb_save_area *vmsa;
+ struct sev_es_save_area *vmsa;
struct ghcb *ghcb;
struct kvm_host_map ghcb_map;
bool received_first_sipi;
--
2.25.1