* [PATCH] book3s_hv_rmhandlers:Pass the correct trap argument to kvmhv_commence_exit
@ 2015-05-21 8:27 Gautham R. Shenoy
2015-08-14 5:07 ` Sam Bobroff
0 siblings, 1 reply; 3+ messages in thread
From: Gautham R. Shenoy @ 2015-05-21 8:27 UTC (permalink / raw)
To: Paul Mackerras, Benjamin Herrenschmidt, Michael Ellerman
Cc: linux-kernel, kvm-ppc, linuxppc-dev, Aneesh Kumar K.V,
Gautham R. Shenoy
In guest_exit_cont we call kvmhv_commence_exit which expects the trap
number as the argument. However r3 doesn't contain the trap number at
this point and as a result we would be calling the function with a
spurious trap number.
Fix this by copying r12 into r3 before calling kvmhv_commence_exit as
r12 contains the trap number
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
---
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 4d70df2..f0d7c54 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1170,6 +1170,7 @@ mc_cont:
bl kvmhv_accumulate_time
#endif
+ mr r3, r12
/* Increment exit count, poke other threads to exit */
bl kvmhv_commence_exit
nop
--
1.9.3
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] book3s_hv_rmhandlers:Pass the correct trap argument to kvmhv_commence_exit
2015-05-21 8:27 [PATCH] book3s_hv_rmhandlers:Pass the correct trap argument to kvmhv_commence_exit Gautham R. Shenoy
@ 2015-08-14 5:07 ` Sam Bobroff
2015-08-17 5:53 ` Gautham R Shenoy
0 siblings, 1 reply; 3+ messages in thread
From: Sam Bobroff @ 2015-08-14 5:07 UTC (permalink / raw)
To: Gautham R. Shenoy
Cc: Paul Mackerras, Benjamin Herrenschmidt, Michael Ellerman,
linuxppc-dev, linux-kernel, kvm-ppc, Aneesh Kumar K.V
On Thu, May 21, 2015 at 01:57:04PM +0530, Gautham R. Shenoy wrote:
> In guest_exit_cont we call kvmhv_commence_exit which expects the trap
> number as the argument. However r3 doesn't contain the trap number at
> this point and as a result we would be calling the function with a
> spurious trap number.
>
> Fix this by copying r12 into r3 before calling kvmhv_commence_exit as
> r12 contains the trap number
>
> Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Hi Gautham,
I agree with your logic: r3 is quite clearly corrupted in that path. So:
Reviewed-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Just one comment: Do you have a case of this causing some visible problem due
to the corrupted trap number? (I'll test the patch if you do.)
Cheers,
Sam.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] book3s_hv_rmhandlers:Pass the correct trap argument to kvmhv_commence_exit
2015-08-14 5:07 ` Sam Bobroff
@ 2015-08-17 5:53 ` Gautham R Shenoy
0 siblings, 0 replies; 3+ messages in thread
From: Gautham R Shenoy @ 2015-08-17 5:53 UTC (permalink / raw)
To: Sam Bobroff
Cc: Gautham R. Shenoy, Paul Mackerras, Benjamin Herrenschmidt,
Michael Ellerman, linuxppc-dev, linux-kernel, kvm-ppc,
Aneesh Kumar K.V
Hi Sam,
On Fri, Aug 14, 2015 at 03:07:28PM +1000, Sam Bobroff wrote:
> On Thu, May 21, 2015 at 01:57:04PM +0530, Gautham R. Shenoy wrote:
> > In guest_exit_cont we call kvmhv_commence_exit which expects the trap
> > number as the argument. However r3 doesn't contain the trap number at
> > this point and as a result we would be calling the function with a
> > spurious trap number.
> >
> > Fix this by copying r12 into r3 before calling kvmhv_commence_exit as
> > r12 contains the trap number
> >
> > Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
>
> Hi Gautham,
>
> I agree with your logic: r3 is quite clearly corrupted in that path. So:
>
> Reviewed-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
>
> Just one comment: Do you have a case of this causing some visible problem due
> to the corrupted trap number? (I'll test the patch if you do.)
>
Actually no! I found this bug while reviewing the code for some other issue.
> Cheers,
> Sam.
--
Thanks and Regards
gautham.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2015-05-21 8:27 [PATCH] book3s_hv_rmhandlers:Pass the correct trap argument to kvmhv_commence_exit Gautham R. Shenoy
2015-08-14 5:07 ` Sam Bobroff
2015-08-17 5:53 ` Gautham R Shenoy
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