1 files changed, 55 insertions, 28 deletions

diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c
index 84c1821819af..75c7df3a0820 100644
--- a/arch/x86/kernel/sev-es.c
+++ b/arch/x86/kernel/sev-es.c
@@ -121,8 +121,18 @@ static void __init setup_vc_stacks(int cpu)
 	cea_set_pte((void *)vaddr, pa, PAGE_KERNEL);
 }
 
-static __always_inline bool on_vc_stack(unsigned long sp)
+static __always_inline bool on_vc_stack(struct pt_regs *regs)
 {
+	unsigned long sp = regs->sp;
+
+	/* User-mode RSP is not trusted */
+	if (user_mode(regs))
+		return false;
+
+	/* SYSCALL gap still has user-mode RSP */
+	if (ip_within_syscall_gap(regs))
+		return false;
+
 	return ((sp >= __this_cpu_ist_bottom_va(VC)) && (sp < __this_cpu_ist_top_va(VC)));
 }
 
@@ -144,7 +154,7 @@ void noinstr __sev_es_ist_enter(struct pt_regs *regs)
 	old_ist = __this_cpu_read(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC]);
 
 	/* Make room on the IST stack */
-	if (on_vc_stack(regs->sp))
+	if (on_vc_stack(regs))
 		new_ist = ALIGN_DOWN(regs->sp, 8) - sizeof(old_ist);
 	else
 		new_ist = old_ist - sizeof(old_ist);
@@ -241,39 +251,54 @@ static int vc_fetch_insn_kernel(struct es_em_ctxt *ctxt,
 	return copy_from_kernel_nofault(buffer, (unsigned char *)ctxt->regs->ip, MAX_INSN_SIZE);
 }
 
-static enum es_result vc_decode_insn(struct es_em_ctxt *ctxt)
+static enum es_result __vc_decode_user_insn(struct es_em_ctxt *ctxt)
 {
 	char buffer[MAX_INSN_SIZE];
-	enum es_result ret;
 	int res;
 
-	if (user_mode(ctxt->regs)) {
-		res = insn_fetch_from_user(ctxt->regs, buffer);
-		if (!res) {
-			ctxt->fi.vector     = X86_TRAP_PF;
-			ctxt->fi.error_code = X86_PF_INSTR | X86_PF_USER;
-			ctxt->fi.cr2        = ctxt->regs->ip;
-			return ES_EXCEPTION;
-		}
+	res = insn_fetch_from_user_inatomic(ctxt->regs, buffer);
+	if (!res) {
+		ctxt->fi.vector     = X86_TRAP_PF;
+		ctxt->fi.error_code = X86_PF_INSTR | X86_PF_USER;
+		ctxt->fi.cr2        = ctxt->regs->ip;
+		return ES_EXCEPTION;
+	}
 
-		if (!insn_decode(&ctxt->insn, ctxt->regs, buffer, res))
-			return ES_DECODE_FAILED;
-	} else {
-		res = vc_fetch_insn_kernel(ctxt, buffer);
-		if (res) {
-			ctxt->fi.vector     = X86_TRAP_PF;
-			ctxt->fi.error_code = X86_PF_INSTR;
-			ctxt->fi.cr2        = ctxt->regs->ip;
-			return ES_EXCEPTION;
-		}
+	if (!insn_decode_from_regs(&ctxt->insn, ctxt->regs, buffer, res))
+		return ES_DECODE_FAILED;
+
+	if (ctxt->insn.immediate.got)
+		return ES_OK;
+	else
+		return ES_DECODE_FAILED;
+}
+
+static enum es_result __vc_decode_kern_insn(struct es_em_ctxt *ctxt)
+{
+	char buffer[MAX_INSN_SIZE];
+	int res, ret;
 
-		insn_init(&ctxt->insn, buffer, MAX_INSN_SIZE - res, 1);
-		insn_get_length(&ctxt->insn);
+	res = vc_fetch_insn_kernel(ctxt, buffer);
+	if (res) {
+		ctxt->fi.vector     = X86_TRAP_PF;
+		ctxt->fi.error_code = X86_PF_INSTR;
+		ctxt->fi.cr2        = ctxt->regs->ip;
+		return ES_EXCEPTION;
 	}
 
-	ret = ctxt->insn.immediate.got ? ES_OK : ES_DECODE_FAILED;
+	ret = insn_decode(&ctxt->insn, buffer, MAX_INSN_SIZE, INSN_MODE_64);
+	if (ret < 0)
+		return ES_DECODE_FAILED;
+	else
+		return ES_OK;
+}
 
-	return ret;
+static enum es_result vc_decode_insn(struct es_em_ctxt *ctxt)
+{
+	if (user_mode(ctxt->regs))
+		return __vc_decode_user_insn(ctxt);
+	else
+		return __vc_decode_kern_insn(ctxt);
 }
 
 static enum es_result vc_write_mem(struct es_em_ctxt *ctxt,
@@ -1248,13 +1273,12 @@ static __always_inline bool on_vc_fallback_stack(struct pt_regs *regs)
 DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
 {
 	struct sev_es_runtime_data *data = this_cpu_read(runtime_data);
+	irqentry_state_t irq_state;
 	struct ghcb_state state;
 	struct es_em_ctxt ctxt;
 	enum es_result result;
 	struct ghcb *ghcb;
 
-	lockdep_assert_irqs_disabled();
-
 	/*
 	 * Handle #DB before calling into !noinstr code to avoid recursive #DB.
 	 */
@@ -1263,6 +1287,8 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
 		return;
 	}
 
+	irq_state = irqentry_nmi_enter(regs);
+	lockdep_assert_irqs_disabled();
 	instrumentation_begin();
 
 	/*
@@ -1325,6 +1351,7 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
 
 out:
 	instrumentation_end();
+	irqentry_nmi_exit(regs, irq_state);
 
 	return;