Re: [PATCH v3 1/1] KVM: PPC: Book3S: correct width in XER handling

[Thomas Huth <thuth@redhat.com>]

On 05/27/2015 01:56 AM, Sam Bobroff wrote:
> In 64 bit kernels, the Fixed Point Exception Register (XER) is a 64
> bit field (e.g. in kvm_regs and kvm_vcpu_arch) and in most places it is
> accessed as such.
> 
> This patch corrects places where it is accessed as a 32 bit field by a
> 64 bit kernel.  In some cases this is via a 32 bit load or store
> instruction which, depending on endianness, will cause either the
> lower or upper 32 bits to be missed.  In another case it is cast as a
> u32, causing the upper 32 bits to be cleared.
> 
> This patch corrects those places by extending the access methods to
> 64 bits.
> 
> Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>

Reviewed-by: Thomas Huth <thuth@redhat.com>

Actually this patch also fixes a bug that SLOF sometimes crashes when a
vCPU gets kicked out of kernel mode (see the following URL for details:
https://bugzilla.redhat.com/show_bug.cgi?id\x1178502 ), and I've just
tested that this bug does not occur with this patch anymore, so also:

Tested-by: Thomas Huth <thuth@redhat.com>