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KVM: SVM: Create a separate mapping for the SEV-ES save area
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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.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>
Link: https://lore.kernel.org/r/20220405182743.308853-1-brijesh.singh@amd.com
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Tom Lendacky authored and Borislav Petkov committed Apr 6, 2022
1 parent 046f773 commit 3dd2775
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Showing 4 changed files with 82 additions and 35 deletions.
87 changes: 67 additions & 20 deletions arch/x86/include/asm/svm.h
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Original file line number Diff line number Diff line change
Expand Up @@ -271,6 +271,7 @@ 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;
Expand All @@ -287,8 +288,58 @@ 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;
Expand Down Expand Up @@ -316,22 +367,14 @@ 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;
Expand All @@ -343,37 +386,41 @@ 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 */
u32 ghcb_usage;
} __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);
}
Expand Down Expand Up @@ -443,7 +490,7 @@ 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) \
Expand Down
22 changes: 11 additions & 11 deletions arch/x86/kvm/svm/sev.c
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Original file line number Diff line number Diff line change
Expand Up @@ -559,12 +559,20 @@ 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];
Expand Down Expand Up @@ -592,14 +600,6 @@ 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;
}

Expand Down Expand Up @@ -2932,7 +2932,7 @@ void sev_es_vcpu_reset(struct vcpu_svm *svm)
sev_enc_bit));
}

void sev_es_prepare_switch_to_guest(struct vmcb_save_area *hostsa)
void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa)
{
/*
* As an SEV-ES guest, hardware will restore the host state on VMEXIT,
Expand Down
4 changes: 2 additions & 2 deletions arch/x86/kvm/svm/svm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1270,8 +1270,8 @@ static void svm_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
*/
vmsave(__sme_page_pa(sd->save_area));
if (sev_es_guest(vcpu->kvm)) {
struct vmcb_save_area *hostsa;
hostsa = (struct vmcb_save_area *)(page_address(sd->save_area) + 0x400);
struct sev_es_save_area *hostsa;
hostsa = (struct sev_es_save_area *)(page_address(sd->save_area) + 0x400);

sev_es_prepare_switch_to_guest(hostsa);
}
Expand Down
4 changes: 2 additions & 2 deletions arch/x86/kvm/svm/svm.h
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Original file line number Diff line number Diff line change
Expand Up @@ -181,7 +181,7 @@ 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;
Expand Down Expand Up @@ -620,7 +620,7 @@ int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in);
void sev_es_init_vmcb(struct vcpu_svm *svm);
void sev_es_vcpu_reset(struct vcpu_svm *svm);
void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector);
void sev_es_prepare_switch_to_guest(struct vmcb_save_area *hostsa);
void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa);
void sev_es_unmap_ghcb(struct vcpu_svm *svm);

/* vmenter.S */
Expand Down

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