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KVM: PPC: Book3S HV: Handle hypervisor instruction faults better 

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.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Paul Mackerras 2018-10-08 16:30:56 +11:00 committed by Michael Ellerman
parent 95a6432ce9
commit 32eb150aee
2 changed files with 5 additions and 1 deletions
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1
arch/powerpc/include/asm/reg.h
View File

@ -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 */

5
arch/powerpc/kvm/book3s_hv.c
View File

@ -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;
/*