| Message ID | 1330474206-14794-20-git-send-email-agraf@suse.de |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Feb 29, 2012 at 01:09:47AM +0100, 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@suse.de> > > --- > > v1 -> v2: > > - fix whitespace Still broken. > - use explicit preempt counts > --- > 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..f7dc3f6 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 > + li r7, 1 > + stw r7, TI_PREEMPT(r8) > + > 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 > +.previous > +.section __ex_table,"a" > + PPC_LONG_ALIGN > + PPC_LONG 1b,3b > +.previous > + > mtspr SPRN_EPLC, r3 > + li r7, 0 > + stw r7, TI_PREEMPT(r8) > stw r9, VCPU_LAST_INST(r4) > .endif -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/powerpc/kvm/bookehv_interrupts.S b/arch/powerpc/kvm/bookehv_interrupts.S index 63023ae..f7dc3f6 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 + li r7, 1 + stw r7, TI_PREEMPT(r8) + 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 +.previous +.section __ex_table,"a" + PPC_LONG_ALIGN + PPC_LONG 1b,3b +.previous + mtspr SPRN_EPLC, r3 + li r7, 0 + stw r7, TI_PREEMPT(r8) stw r9, VCPU_LAST_INST(r4) .endif
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@suse.de> --- v1 -> v2: - fix whitespace - use explicit preempt counts --- arch/powerpc/kvm/bookehv_interrupts.S | 30 +++++++++++++++++++++++++++++- 1 files changed, 29 insertions(+), 1 deletions(-)