2022-03-17 04:40:20

by Borislav Petkov

Subject: Re: system locks up with CONFIG_SLS=Y; 5.17.0-rc

On Wed, Mar 16, 2022 at 06:45:25PM +0000, Jamie Heilman wrote:
> Yep that worked, here's output, you can see the network get set up and
> then boom:

Thx, that was very useful. Does this below fix it, per chance:

---
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index f667bd8df533..e88ce4171c4a 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -430,8 +430,11 @@ static int fastop(struct x86_emulate_ctxt *ctxt, fastop_t fop);
FOP_END

/* Special case for SETcc - 1 instruction per cc */
+
+#define SETCC_ALIGN 8
+
#define FOP_SETCC(op) \
- ".align 4 \n\t" \
+ ".align " __stringify(SETCC_ALIGN) " \n\t" \
".type " #op ", @function \n\t" \
#op ": \n\t" \
ASM_ENDBR \
@@ -1049,7 +1052,7 @@ static int em_bsr_c(struct x86_emulate_ctxt *ctxt)
static __always_inline u8 test_cc(unsigned int condition, unsigned long flags)
{
u8 rc;
- void (*fop)(void) = (void *)em_setcc + 4 * (condition & 0xf);
+ void (*fop)(void) = (void *)em_setcc + SETCC_ALIGN * (condition & 0xf);

flags = (flags & EFLAGS_MASK) | X86_EFLAGS_IF;
asm("push %[flags]; popf; " CALL_NOSPEC

--
Regards/Gruss,
Boris.

https://people.kernel.org/tglx/notes-about-netiquette

2022-03-17 06:05:36

by Jamie Heilman

Subject: Re: system locks up with CONFIG_SLS=Y; 5.17.0-rc

Borislav Petkov wrote:
> On Wed, Mar 16, 2022 at 06:45:25PM +0000, Jamie Heilman wrote:
> > Yep that worked, here's output, you can see the network get set up and
> > then boom:
>
> Thx, that was very useful. Does this below fix it, per chance:

It does indeed!

> ---
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index f667bd8df533..e88ce4171c4a 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -430,8 +430,11 @@ static int fastop(struct x86_emulate_ctxt *ctxt, fastop_t fop);
> FOP_END
>
> /* Special case for SETcc - 1 instruction per cc */
> +
> +#define SETCC_ALIGN 8
> +
> #define FOP_SETCC(op) \
> - ".align 4 \n\t" \
> + ".align " __stringify(SETCC_ALIGN) " \n\t" \
> ".type " #op ", @function \n\t" \
> #op ": \n\t" \
> ASM_ENDBR \
> @@ -1049,7 +1052,7 @@ static int em_bsr_c(struct x86_emulate_ctxt *ctxt)
> static __always_inline u8 test_cc(unsigned int condition, unsigned long flags)
> {
> u8 rc;
> - void (*fop)(void) = (void *)em_setcc + 4 * (condition & 0xf);
> + void (*fop)(void) = (void *)em_setcc + SETCC_ALIGN * (condition & 0xf);
>
> flags = (flags & EFLAGS_MASK) | X86_EFLAGS_IF;
> asm("push %[flags]; popf; " CALL_NOSPEC
>
> --
> Regards/Gruss,
> Boris.
>
> https://people.kernel.org/tglx/notes-about-netiquette

--
Jamie Heilman http://audible.transient.net/~jamie/