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Joerg Roedel

2021-Jun-10 09:11 UTC

[PATCH v4 0/6] x86/sev-es: Fixes for SEV-ES Guest Support

From: Joerg Roedel <jroedel at suse.de>

Hi,

here is the next revision of my pending fixes for Linux' SEV-ES
support. Changes to the previous version are:

	- Removed first patch which is now in tip/x86/urgent already
	- Removed patch "x86/sev-es: Run #VC handler in plain IRQ state"
	  and replaced it with
	  "x86/sev-es: Split up runtime #VC handler for correct state
tracking"
	  as per suggestion from PeterZ

Changes are based on tip/x86/urgent. Please review.

Thanks,

	Joerg

Joerg Roedel (6):
  x86/sev-es: Fix error message in runtime #VC handler
  x86/sev-es: Disable IRQs while GHCB is active
  x86/sev-es: Split up runtime #VC handler for correct state tracking
  x86/insn-eval: Make 0 a valid RIP for insn_get_effective_ip()
  x86/insn: Extend error reporting from
    insn_fetch_from_user[_inatomic]()
  x86/sev-es: Propagate #GP if getting linear instruction address failed

 arch/x86/kernel/sev.c    | 174 +++++++++++++++++++++++----------------
 arch/x86/kernel/umip.c   |  10 +--
 arch/x86/lib/insn-eval.c |  22 +++--
 3 files changed, 122 insertions(+), 84 deletions(-)


base-commit: efa165504943f2128d50f63de0c02faf6dcceb0d
-- 
2.31.1

Joerg Roedel

2021-Jun-10 09:11 UTC

head link

[PATCH v4 1/6] x86/sev-es: Fix error message in runtime #VC handler

From: Joerg Roedel <jroedel at suse.de>

The runtime #VC handler is not "early" anymore. Fix the copy&paste
error
and remove that word from the error message.

Signed-off-by: Joerg Roedel <jroedel at suse.de>
---
 arch/x86/kernel/sev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 651b81cd648e..4fd997bbf059 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -1369,7 +1369,7 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
 		vc_finish_insn(&ctxt);
 		break;
 	case ES_UNSUPPORTED:
-		pr_err_ratelimited("Unsupported exit-code 0x%02lx in early #VC exception
(IP: 0x%lx)\n",
+		pr_err_ratelimited("Unsupported exit-code 0x%02lx in #VC exception (IP:
0x%lx)\n",
 				   error_code, regs->ip);
 		goto fail;
 	case ES_VMM_ERROR:
-- 
2.31.1

Joerg Roedel

2021-Jun-10 09:11 UTC

head link

[PATCH v4 2/6] x86/sev-es: Disable IRQs while GHCB is active

From: Joerg Roedel <jroedel at suse.de>

The #VC handler only cares about IRQs being disabled while the GHCB is
active, as it must not be interrupted by something which could cause
another #VC while it holds the GHCB (NMI is the exception for which the
backup GHCB is there).

Make sure nothing interrupts the code path while the GHCB is active by
disabling IRQs in sev_es_get_ghcb() and restoring the previous irq state
in sev_es_put_ghcb().

Signed-off-by: Joerg Roedel <jroedel at suse.de>
---
 arch/x86/kernel/sev.c | 39 +++++++++++++++++++++++++--------------
 1 file changed, 25 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 4fd997bbf059..2a922d1b03c8 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -192,14 +192,23 @@ void noinstr __sev_es_ist_exit(void)
 	this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], *(unsigned long *)ist);
 }
 
-static __always_inline struct ghcb *sev_es_get_ghcb(struct ghcb_state *state)
+static __always_inline struct ghcb *sev_es_get_ghcb(struct ghcb_state *state,
+						    unsigned long *flags)
 {
 	struct sev_es_runtime_data *data;
 	struct ghcb *ghcb;
 
+	/*
+	 * Nothing shall interrupt this code path while holding the per-cpu
+	 * GHCB. The backup GHCB is only for NMIs interrupting this path.
+	 */
+	local_irq_save(*flags);
+
 	data = this_cpu_read(runtime_data);
 	ghcb = &data->ghcb_page;
 
+
+
 	if (unlikely(data->ghcb_active)) {
 		/* GHCB is already in use - save its contents */
 
@@ -479,7 +488,8 @@ static enum es_result vc_slow_virt_to_phys(struct ghcb
*ghcb, struct es_em_ctxt
 /* Include code shared with pre-decompression boot stage */
 #include "sev-shared.c"
 
-static __always_inline void sev_es_put_ghcb(struct ghcb_state *state)
+static __always_inline void sev_es_put_ghcb(struct ghcb_state *state,
+					    unsigned long flags)
 {
 	struct sev_es_runtime_data *data;
 	struct ghcb *ghcb;
@@ -500,14 +510,17 @@ static __always_inline void sev_es_put_ghcb(struct
ghcb_state *state)
 		vc_ghcb_invalidate(ghcb);
 		data->ghcb_active = false;
 	}
+
+	local_irq_restore(flags);
 }
 
 void noinstr __sev_es_nmi_complete(void)
 {
 	struct ghcb_state state;
+	unsigned long flags;
 	struct ghcb *ghcb;
 
-	ghcb = sev_es_get_ghcb(&state);
+	ghcb = sev_es_get_ghcb(&state, &flags);
 
 	vc_ghcb_invalidate(ghcb);
 	ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_NMI_COMPLETE);
@@ -517,7 +530,7 @@ void noinstr __sev_es_nmi_complete(void)
 	sev_es_wr_ghcb_msr(__pa_nodebug(ghcb));
 	VMGEXIT();
 
-	sev_es_put_ghcb(&state);
+	sev_es_put_ghcb(&state, flags);
 }
 
 static u64 get_jump_table_addr(void)
@@ -527,9 +540,7 @@ static u64 get_jump_table_addr(void)
 	struct ghcb *ghcb;
 	u64 ret = 0;
 
-	local_irq_save(flags);
-
-	ghcb = sev_es_get_ghcb(&state);
+	ghcb = sev_es_get_ghcb(&state, &flags);
 
 	vc_ghcb_invalidate(ghcb);
 	ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_JUMP_TABLE);
@@ -543,9 +554,7 @@ static u64 get_jump_table_addr(void)
 	    ghcb_sw_exit_info_2_is_valid(ghcb))
 		ret = ghcb->save.sw_exit_info_2;
 
-	sev_es_put_ghcb(&state);
-
-	local_irq_restore(flags);
+	sev_es_put_ghcb(&state, flags);
 
 	return ret;
 }
@@ -666,9 +675,10 @@ static bool __init sev_es_setup_ghcb(void)
 static void sev_es_ap_hlt_loop(void)
 {
 	struct ghcb_state state;
+	unsigned long flags;
 	struct ghcb *ghcb;
 
-	ghcb = sev_es_get_ghcb(&state);
+	ghcb = sev_es_get_ghcb(&state, &flags);
 
 	while (true) {
 		vc_ghcb_invalidate(ghcb);
@@ -685,7 +695,7 @@ static void sev_es_ap_hlt_loop(void)
 			break;
 	}
 
-	sev_es_put_ghcb(&state);
+	sev_es_put_ghcb(&state, flags);
 }
 
 /*
@@ -1333,6 +1343,7 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
 	struct ghcb_state state;
 	struct es_em_ctxt ctxt;
 	enum es_result result;
+	unsigned long flags;
 	struct ghcb *ghcb;
 
 	/*
@@ -1353,7 +1364,7 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
 	 * keep the IRQs disabled to protect us against concurrent TLB flushes.
 	 */
 
-	ghcb = sev_es_get_ghcb(&state);
+	ghcb = sev_es_get_ghcb(&state, &flags);
 
 	vc_ghcb_invalidate(ghcb);
 	result = vc_init_em_ctxt(&ctxt, regs, error_code);
@@ -1361,7 +1372,7 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
 	if (result == ES_OK)
 		result = vc_handle_exitcode(&ctxt, ghcb, error_code);
 
-	sev_es_put_ghcb(&state);
+	sev_es_put_ghcb(&state, flags);
 
 	/* Done - now check the result */
 	switch (result) {
-- 
2.31.1

Joerg Roedel

2021-Jun-10 09:11 UTC

head link

[PATCH v4 3/6] x86/sev-es: Split up runtime #VC handler for correct state tracking

From: Joerg Roedel <jroedel at suse.de>

Split up the #VC handler code into a from-user and a from-kernel part.
This allows clean and correct state tracking, as the #VC handler needs
to enter NMI-state when raised from kernel mode and plain IRQ state when
raised from user-mode.

Fixes: 62441a1fb532 ("x86/sev-es: Correctly track IRQ states in runtime #VC
handler")
Suggested-by: Peter Zijlstra <peterz at infradead.org>
Signed-off-by: Joerg Roedel <jroedel at suse.de>
---
 arch/x86/kernel/sev.c | 118 ++++++++++++++++++++++++------------------
 1 file changed, 68 insertions(+), 50 deletions(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 2a922d1b03c8..475bbc1b3547 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -1326,43 +1326,14 @@ static __always_inline bool on_vc_fallback_stack(struct
pt_regs *regs)
 	return (sp >= __this_cpu_ist_bottom_va(VC2) && sp <
__this_cpu_ist_top_va(VC2));
 }
 
-/*
- * Main #VC exception handler. It is called when the entry code was able to
- * switch off the IST to a safe kernel stack.
- *
- * With the current implementation it is always possible to switch to a safe
- * stack because #VC exceptions only happen at known places, like intercepted
- * instructions or accesses to MMIO areas/IO ports. They can also happen with
- * code instrumentation when the hypervisor intercepts #DB, but the critical
- * paths are forbidden to be instrumented, so #DB exceptions currently also
- * only happen in safe places.
- */
-DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
+static bool vc_raw_handle_exception(struct pt_regs *regs, unsigned long
error_code)
 {
-	irqentry_state_t irq_state;
 	struct ghcb_state state;
 	struct es_em_ctxt ctxt;
 	enum es_result result;
 	unsigned long flags;
 	struct ghcb *ghcb;
-
-	/*
-	 * Handle #DB before calling into !noinstr code to avoid recursive #DB.
-	 */
-	if (error_code == SVM_EXIT_EXCP_BASE + X86_TRAP_DB) {
-		vc_handle_trap_db(regs);
-		return;
-	}
-
-	irq_state = irqentry_nmi_enter(regs);
-	lockdep_assert_irqs_disabled();
-	instrumentation_begin();
-
-	/*
-	 * This is invoked through an interrupt gate, so IRQs are disabled. The
-	 * code below might walk page-tables for user or kernel addresses, so
-	 * keep the IRQs disabled to protect us against concurrent TLB flushes.
-	 */
+	bool ret = true;
 
 	ghcb = sev_es_get_ghcb(&state, &flags);
 
@@ -1382,15 +1353,18 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
 	case ES_UNSUPPORTED:
 		pr_err_ratelimited("Unsupported exit-code 0x%02lx in #VC exception (IP:
0x%lx)\n",
 				   error_code, regs->ip);
-		goto fail;
+		ret = false;
+		break;
 	case ES_VMM_ERROR:
 		pr_err_ratelimited("Failure in communication with VMM (exit-code 0x%02lx
IP: 0x%lx)\n",
 				   error_code, regs->ip);
-		goto fail;
+		ret = false;
+		break;
 	case ES_DECODE_FAILED:
 		pr_err_ratelimited("Failed to decode instruction (exit-code 0x%02lx IP:
0x%lx)\n",
 				   error_code, regs->ip);
-		goto fail;
+		ret = false;
+		break;
 	case ES_EXCEPTION:
 		vc_forward_exception(&ctxt);
 		break;
@@ -1406,24 +1380,16 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
 		BUG();
 	}
 
-out:
-	instrumentation_end();
-	irqentry_nmi_exit(regs, irq_state);
+	return ret;
+}
 
-	return;
+static void vc_handle_from_kernel(struct pt_regs *regs, unsigned long
error_code)
+{
+	irqentry_state_t irq_state = irqentry_nmi_enter(regs);
 
-fail:
-	if (user_mode(regs)) {
-		/*
-		 * Do not kill the machine if user-space triggered the
-		 * exception. Send SIGBUS instead and let user-space deal with
-		 * it.
-		 */
-		force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)0);
-	} else {
-		pr_emerg("PANIC: Unhandled #VC exception in kernel space
(result=%d)\n",
-			 result);
+	instrumentation_begin();
 
+	if (!vc_raw_handle_exception(regs, error_code)) {
 		/* Show some debug info */
 		show_regs(regs);
 
@@ -1434,7 +1400,59 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
 		panic("Returned from Terminate-Request to Hypervisor\n");
 	}
 
-	goto out;
+	instrumentation_end();
+	irqentry_nmi_exit(regs, irq_state);
+}
+
+static void vc_handle_from_user(struct pt_regs *regs, unsigned long error_code)
+{
+	irqentry_state_t irq_state = irqentry_enter(regs);
+
+	instrumentation_begin();
+
+	if (!vc_raw_handle_exception(regs, error_code)) {
+		/*
+		 * Do not kill the machine if user-space triggered the
+		 * exception. Send SIGBUS instead and let user-space deal with
+		 * it.
+		 */
+		force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)0);
+	}
+
+	instrumentation_end();
+	irqentry_exit(regs, irq_state);
+}
+/*
+ * Main #VC exception handler. It is called when the entry code was able to
+ * switch off the IST to a safe kernel stack.
+ *
+ * With the current implementation it is always possible to switch to a safe
+ * stack because #VC exceptions only happen at known places, like intercepted
+ * instructions or accesses to MMIO areas/IO ports. They can also happen with
+ * code instrumentation when the hypervisor intercepts #DB, but the critical
+ * paths are forbidden to be instrumented, so #DB exceptions currently also
+ * only happen in safe places.
+ */
+DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
+{
+	/*
+	 * Handle #DB before calling into !noinstr code to avoid recursive #DB.
+	 */
+	if (error_code == SVM_EXIT_EXCP_BASE + X86_TRAP_DB) {
+		vc_handle_trap_db(regs);
+		return;
+	}
+
+	/*
+	 * This is invoked through an interrupt gate, so IRQs are disabled. The
+	 * code below might walk page-tables for user or kernel addresses, so
+	 * keep the IRQs disabled to protect us against concurrent TLB flushes.
+	 */
+
+	if (user_mode(regs))
+		vc_handle_from_user(regs, error_code);
+	else
+		vc_handle_from_kernel(regs, error_code);
 }
 
 /* This handler runs on the #VC fall-back stack. It can cause further #VC
exceptions */
-- 
2.31.1

Joerg Roedel

2021-Jun-10 09:11 UTC

head link

[PATCH v4 4/6] x86/insn-eval: Make 0 a valid RIP for insn_get_effective_ip()

From: Joerg Roedel <jroedel at suse.de>

In theory 0 is a valid value for the instruction pointer, so don't use
it as the error return value from insn_get_effective_ip().

Signed-off-by: Joerg Roedel <jroedel at suse.de>
---
 arch/x86/lib/insn-eval.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c
index a67afd74232c..4eecb9c7c6a0 100644
--- a/arch/x86/lib/insn-eval.c
+++ b/arch/x86/lib/insn-eval.c
@@ -1417,7 +1417,7 @@ void __user *insn_get_addr_ref(struct insn *insn, struct
pt_regs *regs)
 	}
 }
 
-static unsigned long insn_get_effective_ip(struct pt_regs *regs)
+static int insn_get_effective_ip(struct pt_regs *regs, unsigned long *ip)
 {
 	unsigned long seg_base = 0;
 
@@ -1430,10 +1430,12 @@ static unsigned long insn_get_effective_ip(struct
pt_regs *regs)
 	if (!user_64bit_mode(regs)) {
 		seg_base = insn_get_seg_base(regs, INAT_SEG_REG_CS);
 		if (seg_base == -1L)
-			return 0;
+			return -EINVAL;
 	}
 
-	return seg_base + regs->ip;
+	*ip = seg_base + regs->ip;
+
+	return 0;
 }
 
 /**
@@ -1455,8 +1457,7 @@ int insn_fetch_from_user(struct pt_regs *regs, unsigned
char buf[MAX_INSN_SIZE])
 	unsigned long ip;
 	int not_copied;
 
-	ip = insn_get_effective_ip(regs);
-	if (!ip)
+	if (insn_get_effective_ip(regs, &ip))
 		return 0;
 
 	not_copied = copy_from_user(buf, (void __user *)ip, MAX_INSN_SIZE);
@@ -1484,8 +1485,7 @@ int insn_fetch_from_user_inatomic(struct pt_regs *regs,
unsigned char buf[MAX_IN
 	unsigned long ip;
 	int not_copied;
 
-	ip = insn_get_effective_ip(regs);
-	if (!ip)
+	if (insn_get_effective_ip(regs, &ip))
 		return 0;
 
 	not_copied = __copy_from_user_inatomic(buf, (void __user *)ip, MAX_INSN_SIZE);
-- 
2.31.1

Joerg Roedel

2021-Jun-10 09:11 UTC

head link

[PATCH v4 5/6] x86/insn: Extend error reporting from insn_fetch_from_user[_inatomic]()

From: Joerg Roedel <jroedel at suse.de>

The error reporting from the insn_fetch_from_user*() functions is not
very verbose. Extend it to include information on whether the linear
RIP could not be calculated or whether the memory access faulted.

This will be used in the SEV-ES code to propagate the correct
exception depending on what went wrong during instruction fetch.

Signed-off-by: Joerg Roedel <jroedel at suse.de>
---
 arch/x86/kernel/sev.c    |  8 ++++----
 arch/x86/kernel/umip.c   | 10 ++++------
 arch/x86/lib/insn-eval.c |  8 ++++++--
 3 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 475bbc1b3547..a7045a5a94ca 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -267,17 +267,17 @@ static int vc_fetch_insn_kernel(struct es_em_ctxt *ctxt,
 static enum es_result __vc_decode_user_insn(struct es_em_ctxt *ctxt)
 {
 	char buffer[MAX_INSN_SIZE];
-	int res;
+	int insn_bytes;
 
-	res = insn_fetch_from_user_inatomic(ctxt->regs, buffer);
-	if (!res) {
+	insn_bytes = insn_fetch_from_user_inatomic(ctxt->regs, buffer);
+	if (insn_bytes <= 0) {
 		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_from_regs(&ctxt->insn, ctxt->regs, buffer, res))
+	if (!insn_decode_from_regs(&ctxt->insn, ctxt->regs, buffer,
insn_bytes))
 		return ES_DECODE_FAILED;
 
 	if (ctxt->insn.immediate.got)
diff --git a/arch/x86/kernel/umip.c b/arch/x86/kernel/umip.c
index 8daa70b0d2da..337178809c89 100644
--- a/arch/x86/kernel/umip.c
+++ b/arch/x86/kernel/umip.c
@@ -346,14 +346,12 @@ bool fixup_umip_exception(struct pt_regs *regs)
 	if (!regs)
 		return false;
 
-	nr_copied = insn_fetch_from_user(regs, buf);
-
 	/*
-	 * The insn_fetch_from_user above could have failed if user code
-	 * is protected by a memory protection key. Give up on emulation
-	 * in such a case.  Should we issue a page fault?
+	 * Give up on emulation if fetching the instruction failed. Should we
+	 * issue a page fault or a #GP?
 	 */
-	if (!nr_copied)
+	nr_copied = insn_fetch_from_user(regs, buf);
+	if (nr_copied <= 0)
 		return false;
 
 	if (!insn_decode_from_regs(&insn, regs, buf, nr_copied))
diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c
index 4eecb9c7c6a0..1b5cdf8b7a4e 100644
--- a/arch/x86/lib/insn-eval.c
+++ b/arch/x86/lib/insn-eval.c
@@ -1451,6 +1451,8 @@ static int insn_get_effective_ip(struct pt_regs *regs,
unsigned long *ip)
  * Number of instruction bytes copied.
  *
  * 0 if nothing was copied.
+ *
+ * -EINVAL if the linear address of the instruction could not be calculated
  */
 int insn_fetch_from_user(struct pt_regs *regs, unsigned char
buf[MAX_INSN_SIZE])
 {
@@ -1458,7 +1460,7 @@ int insn_fetch_from_user(struct pt_regs *regs, unsigned
char buf[MAX_INSN_SIZE])
 	int not_copied;
 
 	if (insn_get_effective_ip(regs, &ip))
-		return 0;
+		return -EINVAL;
 
 	not_copied = copy_from_user(buf, (void __user *)ip, MAX_INSN_SIZE);
 
@@ -1479,6 +1481,8 @@ int insn_fetch_from_user(struct pt_regs *regs, unsigned
char buf[MAX_INSN_SIZE])
  * Number of instruction bytes copied.
  *
  * 0 if nothing was copied.
+ *
+ * -EINVAL if the linear address of the instruction could not be calculated
  */
 int insn_fetch_from_user_inatomic(struct pt_regs *regs, unsigned char
buf[MAX_INSN_SIZE])
 {
@@ -1486,7 +1490,7 @@ int insn_fetch_from_user_inatomic(struct pt_regs *regs,
unsigned char buf[MAX_IN
 	int not_copied;
 
 	if (insn_get_effective_ip(regs, &ip))
-		return 0;
+		return -EINVAL;
 
 	not_copied = __copy_from_user_inatomic(buf, (void __user *)ip, MAX_INSN_SIZE);
 
-- 
2.31.1

Joerg Roedel

2021-Jun-10 09:11 UTC

head link

[PATCH v4 6/6] x86/sev-es: Propagate #GP if getting linear instruction address failed

From: Joerg Roedel <jroedel at suse.de>

When an instruction is fetched from user-space, segmentation needs to
be taken into account. This means that getting the linear address of
an instruction can fail. Hardware would raise a #GP
exception in that case, but the #VC exception handler would emulate it
as a page-fault.

The insn_fetch_from_user*() functions now provide the relevant
information in case of an failure. Use that and propagate a #GP when
the linear address of an instruction to fetch could not be calculated.

Signed-off-by: Joerg Roedel <jroedel at suse.de>
---
 arch/x86/kernel/sev.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index a7045a5a94ca..80c0d8385def 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -270,11 +270,18 @@ static enum es_result __vc_decode_user_insn(struct
es_em_ctxt *ctxt)
 	int insn_bytes;
 
 	insn_bytes = insn_fetch_from_user_inatomic(ctxt->regs, buffer);
-	if (insn_bytes <= 0) {
+	if (insn_bytes == 0) {
+		/* Nothing could be copied */
 		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;
+	} else if (insn_bytes == -EINVAL) {
+		/* Effective RIP could not be calculated */
+		ctxt->fi.vector     = X86_TRAP_GP;
+		ctxt->fi.error_code = 0;
+		ctxt->fi.cr2        = 0;
+		return ES_EXCEPTION;
 	}
 
 	if (!insn_decode_from_regs(&ctxt->insn, ctxt->regs, buffer,
insn_bytes))
-- 
2.31.1

Virtualization - Jun 2021 - [PATCH v4 0/6] x86/sev-es: Fixes for SEV-ES Guest Support

[PATCH v4 0/6] x86/sev-es: Fixes for SEV-ES Guest Support

[PATCH v4 1/6] x86/sev-es: Fix error message in runtime #VC handler

[PATCH v4 2/6] x86/sev-es: Disable IRQs while GHCB is active

[PATCH v4 3/6] x86/sev-es: Split up runtime #VC handler for correct state tracking

[PATCH v4 4/6] x86/insn-eval: Make 0 a valid RIP for insn_get_effective_ip()

[PATCH v4 5/6] x86/insn: Extend error reporting from insn_fetch_from_user[_inatomic]()

[PATCH v4 6/6] x86/sev-es: Propagate #GP if getting linear instruction address failed