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Re: [Qemu-devel] [PATCH 05/17] ppc: Fix hreg_store_msr() so that non-HV
From: |
David Gibson |
Subject: |
Re: [Qemu-devel] [PATCH 05/17] ppc: Fix hreg_store_msr() so that non-HV mode cannot alter MSR:HV |
Date: |
Tue, 15 Mar 2016 20:47:11 +1100 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
On Mon, Mar 14, 2016 at 08:29:10PM +0100, Thomas Huth wrote:
> On 14.03.2016 17:56, Cédric Le Goater wrote:
> > From: Benjamin Herrenschmidt <address@hidden>
> >
> > This helper is only used by the various instructions that can alter
> > MSR and not interrupts. Add a comment to that effect to the interrupt
> > code as well in case somebody wants to change this
> >
> > Signed-off-by: Benjamin Herrenschmidt <address@hidden>
> > Reviewed-by: David Gibson <address@hidden>
> > ---
> > target-ppc/excp_helper.c | 8 ++++++--
> > target-ppc/helper_regs.h | 4 ++--
> > 2 files changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/target-ppc/excp_helper.c b/target-ppc/excp_helper.c
> > index c890853d861b..37d4721db63b 100644
> > --- a/target-ppc/excp_helper.c
> > +++ b/target-ppc/excp_helper.c
> > @@ -666,8 +666,12 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int
> > excp_model, int excp)
> > }
> > }
> > #endif
> > - /* XXX: we don't use hreg_store_msr here as already have treated
> > - * any special case that could occur. Just store MSR and update
> > hflags
> > + /* We don't use hreg_store_msr here as already have treated
> > + * any special case that could occur. Just store MSR and update hflags
> > + *
> > + * Note: We *MUST* not use hreg_store_msr() as-is anyway because it
> > + * will prevent setting of the HV bit which some exceptions might need
> > + * to do.
> > */
> > env->msr = new_msr & env->msr_mask;
> > hreg_compute_hflags(env);
> > diff --git a/target-ppc/helper_regs.h b/target-ppc/helper_regs.h
> > index 271fddf17f0a..844240d1a755 100644
> > --- a/target-ppc/helper_regs.h
> > +++ b/target-ppc/helper_regs.h
> > @@ -75,8 +75,8 @@ static inline int hreg_store_msr(CPUPPCState *env,
> > target_ulong value,
> > excp = 0;
> > value &= env->msr_mask;
> > #if !defined(CONFIG_USER_ONLY)
> > - if (!alter_hv) {
> > - /* mtmsr cannot alter the hypervisor state */
> > + /* Neither mtmsr nor guest state can alter HV */
> > + if (!alter_hv || !(env->msr & MSR_HVB)) {
> > value &= ~MSR_HVB;
> > value |= env->msr & MSR_HVB;
> > }
>
> Reviewed-by: Thomas Huth <address@hidden>
This looks correct, but I'm not seeing a strong case for including it
before 2.6.
--
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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- [Qemu-devel] [PATCH 07/17] ppc: Better figure out if processor has HV mode, (continued)
[Qemu-devel] [PATCH 05/17] ppc: Fix hreg_store_msr() so that non-HV mode cannot alter MSR:HV, Cédric Le Goater, 2016/03/14
[Qemu-devel] [PATCH 16/17] ppc: Add dummy CIABR SPR, Cédric Le Goater, 2016/03/14
[Qemu-devel] [PATCH 08/17] ppc: Add placeholder SPRs for DPDES and DHDES on P8, Cédric Le Goater, 2016/03/14
[Qemu-devel] [PATCH 09/17] ppc: SPURR & PURR are HV writeable and privileged, Cédric Le Goater, 2016/03/14