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Date: Fri, 08 Apr 2022 09:08:41 -0000
From: "tip-bot2 for Brijesh Singh" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Brijesh Singh <brijesh.singh@....com>,
Borislav Petkov <bp@...e.de>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip: x86/sev] x86/sev: Provide support for SNP guest request NAEs
The following commit has been merged into the x86/sev branch of tip:
Commit-ID: d5af44dde5461d125d1602ac913ab5c6bdf09b8b
Gitweb: https://git.kernel.org/tip/d5af44dde5461d125d1602ac913ab5c6bdf09b8b
Author: Brijesh Singh <brijesh.singh@....com>
AuthorDate: Mon, 07 Mar 2022 15:33:51 -06:00
Committer: Borislav Petkov <bp@...e.de>
CommitterDate: Thu, 07 Apr 2022 16:47:12 +02:00
x86/sev: Provide support for SNP guest request NAEs
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@....com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-42-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 | 57 ++++++++++++++++++++++++++++++-
4 files changed, 78 insertions(+)
diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
index 0759af9..b8357d6 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 84d3d51..c63a1d4 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 cfea5e8..f69c168 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 70ecc6e..7237b41 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -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);
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