Re: [Qemu-devel] [Qemu-ppc] [PATCH 1/1] ppc: Fix MMU model values needed by PR KVM

[Greg Kurz]

On Fri, 2 Dec 2016 15:42:49 +1100
Sam Bobroff <address@hidden> wrote:

> Ping?
> 

The issue got addressed by this commit:

commit 0d594f5565837fe2886a8aa307ef8abb65eab8f7
Author: Thomas Huth <address@hidden>
Date:   Wed Sep 21 11:42:15 2016 +0200

    ppc/kvm: Mark 64kB page size support as disabled if not available

Cheers.

--
Greg

> On Thu, Jul 21, 2016 at 08:07:25AM +0100, Mark Cave-Ayland wrote:
> > On 21/07/16 06:55, Sam Bobroff wrote:
> >   
> > > Commit 4322e8c "ppc: Fix 64K pages support in full emulation" added
> > > the POWERPC_MMU_64K flag to the POWERPC_MMU_2_06 and POWERPC_MMU_2_07
> > > definitions but not to their "degraded" variants. When running with PR
> > > KVM, kvm_fixup_page_sizes() removes the POWERPC_MMU_1TSEG flag from
> > > the MMU value then later ppc_tlb_invalidate_all() expects the value to
> > > be one from the list, but it isn't because the POWERPC_MMU_64K bit is
> > > missing from the (otherwise) matching "degraded" entry. This causes
> > > QEMU to exit with "fatal: Unknown MMU model".
> > > 
> > > This patch adds the POWERPC_MMU_64K flag to the POWERPC_MMU_2_06a and
> > > POWERPC_MMU_2_07a values, preventing the error.
> > > 
> > > Signed-off-by: Sam Bobroff <address@hidden>
> > > ---
> > > I recently discovered that I can't start QEMU with KVM PR for modern
> > > pseries machines:
> > > 
> > > $ rmmod kvm_hv
> > > $ modprobe kvm-pr
> > > $ qemu-system-ppc64 -nographic -vga none -machine pseries,accel=kvm
> > > qemu: fatal: Unknown MMU model
> > > 
> > > A quick investigation seems to indicate that it's just a missing flag
> > > in the MMU definition. If it's really that simple then here's a patch
> > > for it.
> > > 
> > > Cheers,
> > > Sam.
> > > 
> > >  target-ppc/cpu-qom.h | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > > 
> > > diff --git a/target-ppc/cpu-qom.h b/target-ppc/cpu-qom.h
> > > index 2864105..0f1e011 100644
> > > --- a/target-ppc/cpu-qom.h
> > > +++ b/target-ppc/cpu-qom.h
> > > @@ -71,6 +71,10 @@ enum powerpc_mmu_t {
> > >  #define POWERPC_MMU_1TSEG    0x00020000
> > >  #define POWERPC_MMU_AMR      0x00040000
> > >  #define POWERPC_MMU_64K      0x00080000
> > > +/* Any entry that include POWERPC_MMU_1TSEG must have a matching
> > > + * entry without it, because it may be removed by
> > > + * kvm_fixup_page_sizes() and the new value must exist here.
> > > + * See ppc_tlb_invalidate_*(). */
> > >      /* 64 bits PowerPC MMU                                     */
> > >      POWERPC_MMU_64B        = POWERPC_MMU_64 | 0x00000001,
> > >      /* Architecture 2.03 and later (has LPCR) */
> > > @@ -81,6 +85,7 @@ enum powerpc_mmu_t {
> > >                               | POWERPC_MMU_AMR | 0x00000003,
> > >      /* Architecture 2.06 "degraded" (no 1T segments)           */
> > >      POWERPC_MMU_2_06a      = POWERPC_MMU_64 | POWERPC_MMU_AMR
> > > +                             | POWERPC_MMU_64K
> > >                               | 0x00000003,
> > >      /* Architecture 2.07 variant                               */
> > >      POWERPC_MMU_2_07       = POWERPC_MMU_64 | POWERPC_MMU_1TSEG
> > > @@ -88,6 +93,7 @@ enum powerpc_mmu_t {
> > >                               | POWERPC_MMU_AMR | 0x00000004,
> > >      /* Architecture 2.07 "degraded" (no 1T segments)           */
> > >      POWERPC_MMU_2_07a      = POWERPC_MMU_64 | POWERPC_MMU_AMR
> > > +                             | POWERPC_MMU_64K
> > >                               | 0x00000004,
> > >  };
> > >  
> > >   
> > 
> > Added David as CC to make sure it gets caught by a PPC maintainer.
> > 
> > 
> > ATB,
> > 
> > Mark.
> >   
> 
>