diff mbox series

[5.15,172/207] x86/sev: Fix SEV-ES INS/OUTS instructions for word, dword, and qword

Message ID 20211206145616.220150126@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg Kroah-Hartman Dec. 6, 2021, 2:57 p.m. UTC 
From: Michael Sterritt <sterritt@google.com>

[ Upstream commit 1d5379d0475419085d3575bd9155f2e558e96390 ]

Properly type the operands being passed to __put_user()/__get_user().
Otherwise, these routines truncate data for dependent instructions
(e.g., INSW) and only read/write one byte.

This has been tested by sending a string with REP OUTSW to a port and
then reading it back in with REP INSW on the same port.

Previous behavior was to only send and receive the first char of the
size. For example, word operations for "abcd" would only read/write
"ac". With change, the full string is now written and read back.

Fixes: f980f9c31a923 (x86/sev-es: Compile early handler code into kernel image)
Signed-off-by: Michael Sterritt <sterritt@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Marc Orr <marcorr@google.com>
Reviewed-by: Peter Gonda <pgonda@google.com>
Reviewed-by: Joerg Roedel <jroedel@suse.de>
Link: https://lkml.kernel.org/r/20211119232757.176201-1-sterritt@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kernel/sev.c | 57 +++++++++++++++++++++++++++++--------------
 1 file changed, 39 insertions(+), 18 deletions(-)
diff mbox series

Patch

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 88401675dabb0..a0064cf77e562 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -294,11 +294,6 @@  static enum es_result vc_write_mem(struct es_em_ctxt *ctxt,
 				   char *dst, char *buf, size_t size)
 {
 	unsigned long error_code = X86_PF_PROT | X86_PF_WRITE;
-	char __user *target = (char __user *)dst;
-	u64 d8;
-	u32 d4;
-	u16 d2;
-	u8  d1;
 
 	/*
 	 * This function uses __put_user() independent of whether kernel or user
@@ -320,26 +315,42 @@  static enum es_result vc_write_mem(struct es_em_ctxt *ctxt,
 	 * instructions here would cause infinite nesting.
 	 */
 	switch (size) {
-	case 1:
+	case 1: {
+		u8 d1;
+		u8 __user *target = (u8 __user *)dst;
+
 		memcpy(&d1, buf, 1);
 		if (__put_user(d1, target))
 			goto fault;
 		break;
-	case 2:
+	}
+	case 2: {
+		u16 d2;
+		u16 __user *target = (u16 __user *)dst;
+
 		memcpy(&d2, buf, 2);
 		if (__put_user(d2, target))
 			goto fault;
 		break;
-	case 4:
+	}
+	case 4: {
+		u32 d4;
+		u32 __user *target = (u32 __user *)dst;
+
 		memcpy(&d4, buf, 4);
 		if (__put_user(d4, target))
 			goto fault;
 		break;
-	case 8:
+	}
+	case 8: {
+		u64 d8;
+		u64 __user *target = (u64 __user *)dst;
+
 		memcpy(&d8, buf, 8);
 		if (__put_user(d8, target))
 			goto fault;
 		break;
+	}
 	default:
 		WARN_ONCE(1, "%s: Invalid size: %zu\n", __func__, size);
 		return ES_UNSUPPORTED;
@@ -362,11 +373,6 @@  static enum es_result vc_read_mem(struct es_em_ctxt *ctxt,
 				  char *src, char *buf, size_t size)
 {
 	unsigned long error_code = X86_PF_PROT;
-	char __user *s = (char __user *)src;
-	u64 d8;
-	u32 d4;
-	u16 d2;
-	u8  d1;
 
 	/*
 	 * This function uses __get_user() independent of whether kernel or user
@@ -388,26 +394,41 @@  static enum es_result vc_read_mem(struct es_em_ctxt *ctxt,
 	 * instructions here would cause infinite nesting.
 	 */
 	switch (size) {
-	case 1:
+	case 1: {
+		u8 d1;
+		u8 __user *s = (u8 __user *)src;
+
 		if (__get_user(d1, s))
 			goto fault;
 		memcpy(buf, &d1, 1);
 		break;
-	case 2:
+	}
+	case 2: {
+		u16 d2;
+		u16 __user *s = (u16 __user *)src;
+
 		if (__get_user(d2, s))
 			goto fault;
 		memcpy(buf, &d2, 2);
 		break;
-	case 4:
+	}
+	case 4: {
+		u32 d4;
+		u32 __user *s = (u32 __user *)src;
+
 		if (__get_user(d4, s))
 			goto fault;
 		memcpy(buf, &d4, 4);
 		break;
-	case 8:
+	}
+	case 8: {
+		u64 d8;
+		u64 __user *s = (u64 __user *)src;
 		if (__get_user(d8, s))
 			goto fault;
 		memcpy(buf, &d8, 8);
 		break;
+	}
 	default:
 		WARN_ONCE(1, "%s: Invalid size: %zu\n", __func__, size);
 		return ES_UNSUPPORTED;