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x86/sev: Provide support for SNP guest request NAEs

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Version 2 of GHCB specification provides SNP_GUEST_REQUEST and
SNP_EXT_GUEST_REQUEST NAE that can be used by the SNP guest to
communicate with the PSP.

While at it, add a snp_issue_guest_request() helper that will be used by
driver or other subsystem to issue the request to PSP.

See SEV-SNP firmware and GHCB spec for more details.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-42-brijesh.singh@amd.com
This commit is contained in:
Brijesh Singh 2022-03-07 15:33:51 -06:00 committed by Borislav Petkov
parent ba37a1438a
commit d5af44dde5
4 changed files with 78 additions and 0 deletions
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3
arch/x86/include/asm/sev-common.h
View File

@ -128,6 +128,9 @@ struct snp_psc_desc {
struct psc_entry entries[VMGEXIT_PSC_MAX_ENTRY];
} __packed;
/* Guest message request error code */
#define SNP_GUEST_REQ_INVALID_LEN BIT_ULL(32)
#define GHCB_MSR_TERM_REQ 0x100
#define GHCB_MSR_TERM_REASON_SET_POS 12
#define GHCB_MSR_TERM_REASON_SET_MASK 0xf

14
arch/x86/include/asm/sev.h
View File

@ -87,6 +87,14 @@ extern bool handle_vc_boot_ghcb(struct pt_regs *regs);
#define RMPADJUST_VMSA_PAGE_BIT BIT(16)
/* SNP Guest message request */
struct snp_req_data {
unsigned long req_gpa;
unsigned long resp_gpa;
unsigned long data_gpa;
unsigned int data_npages;
};
#ifdef CONFIG_AMD_MEM_ENCRYPT
extern struct static_key_false sev_es_enable_key;
extern void __sev_es_ist_enter(struct pt_regs *regs);
@ -154,6 +162,7 @@ void snp_set_memory_private(unsigned long vaddr, unsigned int npages);
void snp_set_wakeup_secondary_cpu(void);
bool snp_init(struct boot_params *bp);
void snp_abort(void);
int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned long *fw_err);
#else
static inline void sev_es_ist_enter(struct pt_regs *regs) { }
static inline void sev_es_ist_exit(void) { }
@ -173,6 +182,11 @@ static inline void snp_set_memory_private(unsigned long vaddr, unsigned int npag
static inline void snp_set_wakeup_secondary_cpu(void) { }
static inline bool snp_init(struct boot_params *bp) { return false; }
static inline void snp_abort(void) { }
static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input,
unsigned long *fw_err)
{
return -ENOTTY;
}
#endif
#endif

4
arch/x86/include/uapi/asm/svm.h
View File

@ -109,6 +109,8 @@
#define SVM_VMGEXIT_SET_AP_JUMP_TABLE 0
#define SVM_VMGEXIT_GET_AP_JUMP_TABLE 1
#define SVM_VMGEXIT_PSC 0x80000010
#define SVM_VMGEXIT_GUEST_REQUEST 0x80000011
#define SVM_VMGEXIT_EXT_GUEST_REQUEST 0x80000012
#define SVM_VMGEXIT_AP_CREATION 0x80000013
#define SVM_VMGEXIT_AP_CREATE_ON_INIT 0
#define SVM_VMGEXIT_AP_CREATE 1
@ -225,6 +227,8 @@
{ SVM_VMGEXIT_AP_HLT_LOOP, "vmgexit_ap_hlt_loop" }, \
{ SVM_VMGEXIT_AP_JUMP_TABLE, "vmgexit_ap_jump_table" }, \
{ SVM_VMGEXIT_PSC, "vmgexit_page_state_change" }, \
{ SVM_VMGEXIT_GUEST_REQUEST, "vmgexit_guest_request" }, \
{ SVM_VMGEXIT_EXT_GUEST_REQUEST, "vmgexit_ext_guest_request" }, \
{ SVM_VMGEXIT_AP_CREATION, "vmgexit_ap_creation" }, \
{ SVM_VMGEXIT_HV_FEATURES, "vmgexit_hypervisor_feature" }, \
{ SVM_EXIT_ERR, "invalid_guest_state" }

57
arch/x86/kernel/sev.c
View File

@ -2106,3 +2106,60 @@ static int __init init_sev_config(char *str)
return 1;
}
__setup("sev=", init_sev_config);
int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned long *fw_err)
{
struct ghcb_state state;
struct es_em_ctxt ctxt;
unsigned long flags;
struct ghcb *ghcb;
int ret;
if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
return -ENODEV;
if (!fw_err)
return -EINVAL;
/*
* __sev_get_ghcb() needs to run with IRQs disabled because it is using
* a per-CPU GHCB.
*/
local_irq_save(flags);
ghcb = __sev_get_ghcb(&state);
if (!ghcb) {
ret = -EIO;
goto e_restore_irq;
}
vc_ghcb_invalidate(ghcb);
if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
ghcb_set_rax(ghcb, input->data_gpa);
ghcb_set_rbx(ghcb, input->data_npages);
}
ret = sev_es_ghcb_hv_call(ghcb, true, &ctxt, exit_code, input->req_gpa, input->resp_gpa);
if (ret)
goto e_put;
if (ghcb->save.sw_exit_info_2) {
/* Number of expected pages are returned in RBX */
if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST &&
ghcb->save.sw_exit_info_2 == SNP_GUEST_REQ_INVALID_LEN)
input->data_npages = ghcb_get_rbx(ghcb);
*fw_err = ghcb->save.sw_exit_info_2;
ret = -EIO;
}
e_put:
__sev_put_ghcb(&state);
e_restore_irq:
local_irq_restore(flags);
return ret;
}
EXPORT_SYMBOL_GPL(snp_issue_guest_request);