linux-kernel - [tip: x86/urgent] x86/sev: Fix SEV-ES INS/OUTS instructions for word, dword, and qword

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Message-ID: <163855229549.11128.12985055978691624996.tip-bot2@tip-bot2>
Date:   Fri, 03 Dec 2021 17:24:55 -0000
From:   "tip-bot2 for Michael Sterritt" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Michael Sterritt <sterritt@...gle.com>,
        Borislav Petkov <bp@...e.de>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Marc Orr <marcorr@...gle.com>, Peter Gonda <pgonda@...gle.com>,
        Joerg Roedel <jroedel@...e.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] x86/sev: Fix SEV-ES INS/OUTS instructions for word,
 dword, and qword

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     1d5379d0475419085d3575bd9155f2e558e96390
Gitweb:        https://git.kernel.org/tip/1d5379d0475419085d3575bd9155f2e558e96390
Author:        Michael Sterritt <sterritt@...gle.com>
AuthorDate:    Fri, 19 Nov 2021 15:27:57 -08:00
Committer:     Borislav Petkov <bp@...e.de>
CommitterDate: Fri, 03 Dec 2021 18:09:30 +01:00

x86/sev: Fix SEV-ES INS/OUTS instructions for word, dword, and qword

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@...gle.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>
Reviewed-by: Marc Orr <marcorr@...gle.com>
Reviewed-by: Peter Gonda <pgonda@...gle.com>
Reviewed-by: Joerg Roedel <jroedel@...e.de>
Link: https://lkml.kernel.org/r/20211119232757.176201-1-sterritt@google.com
---
 arch/x86/kernel/sev.c | 57 ++++++++++++++++++++++++++++--------------
 1 file changed, 39 insertions(+), 18 deletions(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 74f0ec9..a9fc2ac 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;