[PATCH] powerpc/kexec: Fix kexec/kdump in P9 guest kernels

[PATCH] powerpc/kexec: Fix kexec/kdump in P9 guest kernels

[Michael Ellerman]

The code that cleans up the IAMR/AMOR before kexec'ing failed to
remember that when we're running as a guest AMOR is not writable, it's
hypervisor privileged.

They symptom is that the kexec stops before entering purgatory and
nothing else is seen on the console. If you examine the state of the
system all threads will be in the 0x700 program check handler.

Fix it by making the write to AMOR dependent on HV mode.

Fixes: 1e2a516e89fc ("powerpc/kexec: Fix radix to hash kexec due to IAMR/AMOR")
Cc: stable@vger.kernel.org # v4.10+
Reported-by: Yilin Zhang <yilzhang@redhat.com>
Debugged-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/kernel/misc_64.S | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
index 8ac0bd2bddb0..3280953a82cf 100644
--- a/arch/powerpc/kernel/misc_64.S
+++ b/arch/powerpc/kernel/misc_64.S
@@ -623,7 +623,9 @@ BEGIN_FTR_SECTION
 	 * NOTE, we rely on r0 being 0 from above.
 	 */
 	mtspr	SPRN_IAMR,r0
+BEGIN_FTR_SECTION_NESTED(42)
 	mtspr	SPRN_AMOR,r0
+END_FTR_SECTION_NESTED_IFSET(CPU_FTR_HVMODE, 42)
 END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
 
 	/* save regs for local vars on new stack.
-- 
2.14.3

Re: [PATCH] powerpc/kexec: Fix kexec/kdump in P9 guest kernels

[Balbir Singh]

On Fri, Nov 24, 2017 at 2:51 PM, Michael Ellerman <mpe@ellerman.id.au> wrote:
> The code that cleans up the IAMR/AMOR before kexec'ing failed to
> remember that when we're running as a guest AMOR is not writable, it's
> hypervisor privileged.
>
> They symptom is that the kexec stops before entering purgatory and
> nothing else is seen on the console. If you examine the state of the
> system all threads will be in the 0x700 program check handler.
>
> Fix it by making the write to AMOR dependent on HV mode.
>
> Fixes: 1e2a516e89fc ("powerpc/kexec: Fix radix to hash kexec due to IAMR/AMOR")
> Cc: stable@vger.kernel.org # v4.10+
> Reported-by: Yilin Zhang <yilzhang@redhat.com>
> Debugged-by: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> ---

Acked-by: Balbir Singh <bsingharora@gmail.com>

Re: [PATCH] powerpc/kexec: Fix kexec/kdump in P9 guest kernels

[David Gibson]

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On Fri, Nov 24, 2017 at 02:51:02PM +1100, Michael Ellerman wrote:
> The code that cleans up the IAMR/AMOR before kexec'ing failed to
> remember that when we're running as a guest AMOR is not writable, it's
> hypervisor privileged.
> 
> They symptom is that the kexec stops before entering purgatory and
> nothing else is seen on the console. If you examine the state of the
> system all threads will be in the 0x700 program check handler.
> 
> Fix it by making the write to AMOR dependent on HV mode.
> 
> Fixes: 1e2a516e89fc ("powerpc/kexec: Fix radix to hash kexec due to IAMR/AMOR")
> Cc: stable@vger.kernel.org # v4.10+
> Reported-by: Yilin Zhang <yilzhang@redhat.com>
> Debugged-by: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Tested-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  arch/powerpc/kernel/misc_64.S | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
> index 8ac0bd2bddb0..3280953a82cf 100644
> --- a/arch/powerpc/kernel/misc_64.S
> +++ b/arch/powerpc/kernel/misc_64.S
> @@ -623,7 +623,9 @@ BEGIN_FTR_SECTION
>  	 * NOTE, we rely on r0 being 0 from above.
>  	 */
>  	mtspr	SPRN_IAMR,r0
> +BEGIN_FTR_SECTION_NESTED(42)
>  	mtspr	SPRN_AMOR,r0
> +END_FTR_SECTION_NESTED_IFSET(CPU_FTR_HVMODE, 42)
>  END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
>  
>  	/* save regs for local vars on new stack.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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Re: powerpc/kexec: Fix kexec/kdump in P9 guest kernels

[Michael Ellerman]

On Fri, 2017-11-24 at 03:51:02 UTC, Michael Ellerman wrote:
> The code that cleans up the IAMR/AMOR before kexec'ing failed to
> remember that when we're running as a guest AMOR is not writable, it's
> hypervisor privileged.
> 
> They symptom is that the kexec stops before entering purgatory and
> nothing else is seen on the console. If you examine the state of the
> system all threads will be in the 0x700 program check handler.
> 
> Fix it by making the write to AMOR dependent on HV mode.
> 
> Fixes: 1e2a516e89fc ("powerpc/kexec: Fix radix to hash kexec due to IAMR/AMOR")
> Cc: stable@vger.kernel.org # v4.10+
> Reported-by: Yilin Zhang <yilzhang@redhat.com>
> Debugged-by: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> Acked-by: Balbir Singh <bsingharora@gmail.com>
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> Tested-by: David Gibson <david@gibson.dropbear.id.au>

Applied to powerpc fixes.

https://git.kernel.org/powerpc/c/2621e945fbf1d6df5f3f0ba7be5bae

cheers