Re: [v3 PATCH 2/5] powerpc/pseries: Fix endainness while restoring of r3 in MCE handler.

On 06/08/2018 12:20 PM, Michael Ellerman wrote:

Mahesh J Salgaonkar [off-list ref] writes:

quoted

From: Mahesh Salgaonkar <redacted>

During Machine Check interrupt on pseries platform, register r3 points
RTAS extended event log passed by hypervisor. Since hypervisor uses r3
to pass pointer to rtas log, it stores the original r3 value at the
start of the memory (first 8 bytes) pointed by r3. Since hypervisor
stores this info and rtas log is in BE format, linux should make
sure to restore r3 value in correct endian format.

Can we hit this under KVM? And if so what if the KVM/qemu is running
little endian, does it still write the value BE?

FWNMI support for qemu is still not in. But when it is in, we can hit
this. But whenever FWNMI support gets in, it should pass RTAS event data
always in BE format including original r3 value.

Thanks,
-Mahesh.

cheers