On 02/17/2012 11:13 AM, Alexander Graf wrote: > There's always a chance we're unable to read a guest instruction. The guest > could have its TLB mapped execute-, but not readable, something odd happens > and our TLB gets flushed. So it's a good idea to be prepared for that case > and have a fallback that allows us to fix things up in that case. > > Add fixup code that keeps guest code from potentially crashing our host kernel. > > Signed-off-by: Alexander Graf <agraf@xxxxxxx> > --- > arch/powerpc/kvm/bookehv_interrupts.S | 30 +++++++++++++++++++++++++++++- > 1 files changed, 29 insertions(+), 1 deletions(-) > > diff --git a/arch/powerpc/kvm/bookehv_interrupts.S b/arch/powerpc/kvm/bookehv_interrupts.S > index 63023ae..e0f484c 100644 > --- a/arch/powerpc/kvm/bookehv_interrupts.S > +++ b/arch/powerpc/kvm/bookehv_interrupts.S > @@ -28,6 +28,7 @@ > #include <asm/asm-compat.h> > #include <asm/asm-offsets.h> > #include <asm/bitsperlong.h> > +#include <asm/thread_info.h> > > #include "../kernel/head_booke.h" /* for THREAD_NORMSAVE() */ > > @@ -171,9 +172,36 @@ > PPC_STL r30, VCPU_GPR(r30)(r4) > PPC_STL r31, VCPU_GPR(r31)(r4) > mtspr SPRN_EPLC, r8 > + > + /* disable preemption, so we are sure we hit the fixup handler */ > +#ifdef CONFIG_PPC64 > + clrrdi r8,r1,THREAD_SHIFT > +#else > + rlwinm r8,r1,0,0,31-THREAD_SHIFT /* current thread_info */ > +#endif > + lwz r6,TI_PREEMPT(r8) > + addi r7,r6,1 > + stw r7,TI_PREEMPT(r8) Whitespace The preempt count had better already be zero here, so we can just store 1 now, and 0 later, and avoid the stall on load results. > + > isync > - lwepx r9, 0, r5 > + > + /* > + * In case the read goes wrong, we catch it and write an invalid value > + * in LAST_INST instead. > + */ > +1: lwepx r9, 0, r5 > +2: > +.section .fixup, "ax" > +3: li r9, KVM_INST_FETCH_FAILED > + b 2b Please tab after the opcode > +.previous > +.section __ex_table,"a" > + PPC_LONG_ALIGN > + PPC_LONG 1b,3b > +.previous > + > mtspr SPRN_EPLC, r3 > + stw r6,TI_PREEMPT(r8) > stw r9, VCPU_LAST_INST(r4) Whitespace -Scott -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
