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Subject[PATCH] Fix SEV-ES INS/OUTS instructions for word, dword, and qword.
From
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.

Tested: 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.

Signed-off-by: Michael Sterritt <sterritt@google.com>
Reviewed-by: Marc Orr <marcorr@google.com>
Reviewed-by: Peter Gonda <pgonda@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 74f0ec955384..a9fc2ac7a8bd 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;
--
2.34.0.rc2.393.gf8c9666880-goog
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