Re: [PATCH] KVM: PPC: Book3S PR: Set hflag to indicate that POWER9 supports 1T segments

On Fri, Dec 07, 2018 at 10:08:20PM +1100, Michael Ellerman wrote:

Suraj Jitindar Singh [off-list ref] writes:

quoted

When booting a kvm-pr guest on a POWER9 machine the following message is
observed:
"qemu-system-ppc64: KVM does not support 1TiB segments which guest expects"

This is because the guest is expecting to be able to use 1T segments
however we don't indicate support for it. This is because we don't set
the BOOK3S_HFLAG_MULTI_PGSIZE flag in the hflags in kvmppc_set_pvr_pr()
on POWER9.

POWER9 does indeed have support for 1T segments, so add a case for
POWER9 to the switch statement to ensure it is set.

If this just checked mmu_has_feature(MMU_FTR_1T_SEGMENT) it would have
been right in this case, and we'd also never have to update it in
future.

Any reason not to?

PR KVM can emulate a different processor from the host.  Checking
mmu_has_feature() will tell you about the host, not the CPU being
emulated.

Paul.