| Message ID | 20220128171804.569796-40-brijesh.singh@amd.com (mailing list archive) |
|---|---|
| State | Deferred, archived |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) Guest Support | expand |
On Fri, Jan 28, 2022 at 10:19 AM Brijesh Singh <brijesh.singh@amd.com> wrote: > > 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> > --- > arch/x86/include/asm/sev-common.h | 3 ++ > arch/x86/include/asm/sev.h | 14 ++++++++ > arch/x86/include/uapi/asm/svm.h | 4 +++ > arch/x86/kernel/sev.c | 55 +++++++++++++++++++++++++++++++ > 4 files changed, 76 insertions(+) > > diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h > index cd769984e929..442614879dad 100644 > --- a/arch/x86/include/asm/sev-common.h > +++ b/arch/x86/include/asm/sev-common.h > @@ -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 > diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h > index 219abb4590f2..9830ee1d6ef0 100644 > --- a/arch/x86/include/asm/sev.h > +++ b/arch/x86/include/asm/sev.h > @@ -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 > diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h > index 8b4c57baec52..5b8bc2b65a5e 100644 > --- a/arch/x86/include/uapi/asm/svm.h > +++ b/arch/x86/include/uapi/asm/svm.h > @@ -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" } > diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c > index cb97200bfda7..1d3ac83226fc 100644 > --- a/arch/x86/kernel/sev.c > +++ b/arch/x86/kernel/sev.c > @@ -2122,3 +2122,58 @@ static int __init snp_check_cpuid_table(void) > } > > arch_initcall(snp_check_cpuid_table); > + > +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; > + > + /* > + * __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); > + > + if (fw_err) > + *fw_err = ghcb->save.sw_exit_info_2; In the PSP driver we've had a bit of discussion around the fw_err and the return code and that it would be preferable to have fw_err be a required parameter. And then we can easily make sure fw_err is always non-zero when the return code is non-zero. Thoughts about doing the same inside the guest? > + > + ret = -EIO; > + } > + > +e_put: > + __sev_put_ghcb(&state); > +e_restore_irq: > + local_irq_restore(flags); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(snp_issue_guest_request); > -- > 2.25.1 >
diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h index cd769984e929..442614879dad 100644 --- a/arch/x86/include/asm/sev-common.h +++ b/arch/x86/include/asm/sev-common.h @@ -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 diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 219abb4590f2..9830ee1d6ef0 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -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 diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h index 8b4c57baec52..5b8bc2b65a5e 100644 --- a/arch/x86/include/uapi/asm/svm.h +++ b/arch/x86/include/uapi/asm/svm.h @@ -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" } diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index cb97200bfda7..1d3ac83226fc 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -2122,3 +2122,58 @@ static int __init snp_check_cpuid_table(void) } arch_initcall(snp_check_cpuid_table); + +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; + + /* + * __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); + + if (fw_err) + *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);
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> --- arch/x86/include/asm/sev-common.h | 3 ++ arch/x86/include/asm/sev.h | 14 ++++++++ arch/x86/include/uapi/asm/svm.h | 4 +++ arch/x86/kernel/sev.c | 55 +++++++++++++++++++++++++++++++ 4 files changed, 76 insertions(+)