diff mbox series

[kvm-unit-tests,v6,08/11] x86: AMD SEV-ES: Handle CPUID #VC

Message ID 20240411172944.23089-9-vsntk18@gmail.com (mailing list archive)
State New, archived
Headers show
Series Add #VC exception handling for AMD SEV-ES | expand

Commit Message

Vasant Karasulli April 11, 2024, 5:29 p.m. UTC 
From: Vasant Karasulli <vkarasulli@suse.de>

Using Linux's CPUID #VC processing logic.

Signed-off-by: Varad Gautam <varad.gautam@suse.com>
Signed-off-by: Vasant Karasulli <vkarasulli@suse.de>
---
 lib/x86/amd_sev.h    |  5 ++-
 lib/x86/amd_sev_vc.c | 97 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 101 insertions(+), 1 deletion(-)

--
2.34.1
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Patch

diff --git a/lib/x86/amd_sev.h b/lib/x86/amd_sev.h
index b6b7a13f..efd439fb 100644
--- a/lib/x86/amd_sev.h
+++ b/lib/x86/amd_sev.h
@@ -71,7 +71,7 @@  struct ghcb {
 	u8 shared_buffer[GHCB_SHARED_BUF_SIZE];

 	u8 reserved_0xff0[10];
-	u16 protocol_version;	/* negotiated SEV-ES/GHCB protocol version */
+	u16 version;	/* version of the GHCB data structure */
 	u32 ghcb_usage;
 } __packed;

@@ -79,6 +79,9 @@  struct ghcb {
 #define GHCB_PROTOCOL_MAX	1ULL
 #define GHCB_DEFAULT_USAGE	0ULL

+/* Version of the GHCB data structure */
+#define GHCB_VERSION		1
+
 #define	VMGEXIT()			{ asm volatile("rep; vmmcall\n\r"); }

 enum es_result {
diff --git a/lib/x86/amd_sev_vc.c b/lib/x86/amd_sev_vc.c
index 30b892f9..3a5e593c 100644
--- a/lib/x86/amd_sev_vc.c
+++ b/lib/x86/amd_sev_vc.c
@@ -8,6 +8,7 @@ 

 #include "amd_sev.h"
 #include "svm.h"
+#include "x86/xsave.h"

 extern phys_addr_t ghcb_addr;

@@ -58,6 +59,99 @@  static void vc_finish_insn(struct es_em_ctxt *ctxt)
 	ctxt->regs->rip += ctxt->insn.length;
 }

+static inline void sev_es_wr_ghcb_msr(u64 val)
+{
+	wrmsr(MSR_AMD64_SEV_ES_GHCB, val);
+}
+
+static inline u64 sev_es_rd_ghcb_msr(void)
+{
+	return rdmsr(MSR_AMD64_SEV_ES_GHCB);
+}
+
+
+static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
+					  struct es_em_ctxt *ctxt,
+					  u64 exit_code, u64 exit_info_1,
+					  u64 exit_info_2)
+{
+	enum es_result ret;
+
+	/* Fill in protocol and format specifiers */
+	ghcb->version = GHCB_VERSION;
+	ghcb->ghcb_usage       = GHCB_DEFAULT_USAGE;
+
+	ghcb_set_sw_exit_code(ghcb, exit_code);
+	ghcb_set_sw_exit_info_1(ghcb, exit_info_1);
+	ghcb_set_sw_exit_info_2(ghcb, exit_info_2);
+
+	sev_es_wr_ghcb_msr(__pa(ghcb));
+	VMGEXIT();
+
+	if ((ghcb->save.sw_exit_info_1 & 0xffffffff) == 1) {
+		u64 info = ghcb->save.sw_exit_info_2;
+		unsigned long v;
+
+		v = info & SVM_EVTINJ_VEC_MASK;
+
+		/* Check if exception information from hypervisor is sane. */
+		if ((info & SVM_EVTINJ_VALID) &&
+		    ((v == GP_VECTOR) || (v == UD_VECTOR)) &&
+		    ((info & SVM_EVTINJ_TYPE_MASK) == SVM_EVTINJ_TYPE_EXEPT)) {
+			ctxt->fi.vector = v;
+			if (info & SVM_EVTINJ_VALID_ERR)
+				ctxt->fi.error_code = info >> 32;
+			ret = ES_EXCEPTION;
+		} else {
+			ret = ES_VMM_ERROR;
+		}
+	} else if (ghcb->save.sw_exit_info_1 & 0xffffffff) {
+		ret = ES_VMM_ERROR;
+	} else {
+		ret = ES_OK;
+	}
+
+	return ret;
+}
+
+static enum es_result vc_handle_cpuid(struct ghcb *ghcb,
+				      struct es_em_ctxt *ctxt)
+{
+	struct ex_regs *regs = ctxt->regs;
+	u32 cr4 = read_cr4();
+	enum es_result ret;
+
+	ghcb_set_rax(ghcb, regs->rax);
+	ghcb_set_rcx(ghcb, regs->rcx);
+
+	if (cr4 & X86_CR4_OSXSAVE) {
+		/* Safe to read xcr0 */
+		u64 xcr0;
+		xgetbv_safe(XCR_XFEATURE_ENABLED_MASK, &xcr0);
+		ghcb_set_xcr0(ghcb, xcr0);
+	} else {
+		/* xgetbv will cause #GP - use reset value for xcr0 */
+		ghcb_set_xcr0(ghcb, 1);
+	}
+
+	ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_CPUID, 0, 0);
+	if (ret != ES_OK)
+		return ret;
+
+	if (!(ghcb_rax_is_valid(ghcb) &&
+	      ghcb_rbx_is_valid(ghcb) &&
+	      ghcb_rcx_is_valid(ghcb) &&
+	      ghcb_rdx_is_valid(ghcb)))
+		return ES_VMM_ERROR;
+
+	regs->rax = ghcb->save.rax;
+	regs->rbx = ghcb->save.rbx;
+	regs->rcx = ghcb->save.rcx;
+	regs->rdx = ghcb->save.rdx;
+
+	return ES_OK;
+}
+
 static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt,
 					 struct ghcb *ghcb,
 					 unsigned long exit_code)
@@ -65,6 +159,9 @@  static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt,
 	enum es_result result;

 	switch (exit_code) {
+	case SVM_EXIT_CPUID:
+		result = vc_handle_cpuid(ghcb, ctxt);
+		break;
 	default:
 		/*
 		 * Unexpected #VC exception