diff mbox series

[v9,39/43] x86/sev: Provide support for SNP guest request NAEs

Message ID 20220128171804.569796-40-brijesh.singh@amd.com
State Superseded
Headers show
Series Add AMD Secure Nested Paging (SEV-SNP) Guest Support | expand

Commit Message

Brijesh Singh Jan. 28, 2022, 5:18 p.m. UTC
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(+)

Comments

Peter Gonda Feb. 1, 2022, 8:17 p.m. UTC | #1
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 mbox series

Patch

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);