possibly revert "KVM: X86 emulator: fix source operand decoding..."

Hi Greg,

The 3.4.44+ cherry pick:

----------------
commit 5b5b30580218eae22609989546bac6e44d0eda6e
Author: Gleb Natapov <[email protected]>
Date: Wed Apr 24 13:38:36 2013 +0300

KVM: X86 emulator: fix source operand decoding for 8bit mov[zs]x instructions

commit 660696d1d16a71e15549ce1bf74953be1592bcd3 upstream.

Source operand for one byte mov[zs]x is decoded incorrectly if it is in high byte register. Fix that.

Signed-off-by Gleb Natapov <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

----------------

introduces the following:

arch/x86/kvm/emulate.c: In function ‘decode_operand’:
arch/x86/kvm/emulate.c:3974:4: warning: passing argument 1 of ‘decode_register’ makes integer from pointer without a cast [enabled by default] arch/x86/kvm/emulate.c:789:14: note: expected ‘u8’ but argument is of type ‘struct x86_emulate_ctxt *’ arch/x86/kvm/emulate.c:3974:4: warning: passing argument 2 of ‘decode_register’ makes pointer from integer without a cast [enabled by default] arch/x86/kvm/emulate.c:789:14: note: expected ‘long unsigned int *’ but argument is of type ‘u8’

Based on the severity of the warnings above, I'm reasonably sure there will be some kind of runtime regressions due to this, but I stopped to investigate the warnings as soon as I saw them, before any run time testing.

It happens because mainline v3.7-rc1~113^2~40 (dd856efafe60) does this:

(quoted diff) +1 -1

-static void *decode_register(u8 modrm_reg, unsigned long *regs,
+static void *decode_register(struct x86_emulate_ctxt *ctxt, u8 modrm_reg,

Since 660696d1d16a71e1 was only applied to stable 3.4, 3.8, and 3.9 -- and the prerequisite above is in 3.7+, the issue should be limited to 3.4.44+

Il 04/09/2013 18:44, Paul Gortmaker ha scritto:

Quoted 34 lines

Hi Greg,

The 3.4.44+ cherry pick:

----------------
commit 5b5b30580218eae22609989546bac6e44d0eda6e
Author: Gleb Natapov <[email protected]>
Date: Wed Apr 24 13:38:36 2013 +0300

KVM: X86 emulator: fix source operand decoding for 8bit mov[zs]x instructions

commit 660696d1d16a71e15549ce1bf74953be1592bcd3 upstream.

Source operand for one byte mov[zs]x is decoded incorrectly if it is in high byte register. Fix that.

Signed-off-by Gleb Natapov <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

----------------

introduces the following:

arch/x86/kvm/emulate.c: In function ‘decode_operand’:
arch/x86/kvm/emulate.c:3974:4: warning: passing argument 1 of ‘decode_register’ makes integer from pointer without a cast [enabled by default] arch/x86/kvm/emulate.c:789:14: note: expected ‘u8’ but argument is of type ‘struct x86_emulate_ctxt *’ arch/x86/kvm/emulate.c:3974:4: warning: passing argument 2 of ‘decode_register’ makes pointer from integer without a cast [enabled by default] arch/x86/kvm/emulate.c:789:14: note: expected ‘long unsigned int *’ but argument is of type ‘u8’

Based on the severity of the warnings above, I'm reasonably sure there will be some kind of runtime regressions due to this, but I stopped to investigate the warnings as soon as I saw them, before any run time testing.

It happens because mainline v3.7-rc1~113^2~40 (dd856efafe60) does this:

Quoted 5 lines

(quoted diff) +1 -1

-static void *decode_register(u8 modrm_reg, unsigned long *regs,
+static void *decode_register(struct x86_emulate_ctxt *ctxt, u8 modrm_reg,

Since 660696d1d16a71e1 was only applied to stable 3.4, 3.8, and 3.9 -- and the prerequisite above is in 3.7+, the issue should be limited to 3.4.44+

Right, the fix is not important to have for 3.4 kernels.