On Fri, Sep 21, 2018 at 08:01:40PM +1000, Paul Mackerras wrote: > Currently the code for handling hypervisor instruction page faults > passes 0 for the flags indicating the type of fault, which is OK in > the usual case that the page is not mapped in the partition-scoped > page tables. However, there are other causes for hypervisor > instruction page faults, such as not being to update a reference > (R) or change (C) bit. The cause is indicated in bits in HSRR1, > including a bit which indicates that the fault is due to not being > able to write to a page (for example to update an R or C bit). > Not handling these other kinds of faults correctly can lead to a > loop of continual faults without forward progress in the guest. > > In order to handle these faults better, this patch constructs a > "DSISR-like" value from the bits which DSISR and SRR1 (for a HISI) > have in common, and passes it to kvmppc_book3s_hv_page_fault() so > that it knows what caused the fault. > > Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx> Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> > --- > arch/powerpc/include/asm/reg.h | 1 + > arch/powerpc/kvm/book3s_hv.c | 5 ++++- > 2 files changed, 5 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h > index e5b314e..6fda746 100644 > --- a/arch/powerpc/include/asm/reg.h > +++ b/arch/powerpc/include/asm/reg.h > @@ -766,6 +766,7 @@ > #define SPRN_HSRR0 0x13A /* Save/Restore Register 0 */ > #define SPRN_HSRR1 0x13B /* Save/Restore Register 1 */ > #define HSRR1_DENORM 0x00100000 /* Denorm exception */ > +#define HSRR1_HISI_WRITE 0x00010000 /* HISI bcs couldn't update mem */ > > #define SPRN_TBCTL 0x35f /* PA6T Timebase control register */ > #define TBCTL_FREEZE 0x0000000000000000ull /* Freeze all tbs */ > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 8576a7b..e0e92f2 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -1188,7 +1188,10 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu, > break; > case BOOK3S_INTERRUPT_H_INST_STORAGE: > vcpu->arch.fault_dar = kvmppc_get_pc(vcpu); > - vcpu->arch.fault_dsisr = 0; > + vcpu->arch.fault_dsisr = vcpu->arch.shregs.msr & > + DSISR_SRR1_MATCH_64S; > + if (vcpu->arch.shregs.msr & HSRR1_HISI_WRITE) > + vcpu->arch.fault_dsisr |= DSISR_ISSTORE; > r = RESUME_PAGE_FAULT; > break; > /* -- 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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