diff options
author | Paul Mackerras <paulus@samba.org> | 2013-08-06 08:15:19 +0400 |
---|---|---|
committer | Alexander Graf <agraf@suse.de> | 2013-08-28 18:47:49 +0400 |
commit | 8b23de29489fd63fce753db9d53055e4bbf8f616 (patch) | |
tree | 94e266d8d7029bbb411568454d0c4df56b52d5fd | |
parent | 9d1ffdd8f34b1f89264effd10e75ea4d6272690e (diff) | |
download | linux-8b23de29489fd63fce753db9d53055e4bbf8f616.tar.xz |
KVM: PPC: Book3S PR: Make instruction fetch fallback work for system calls
It turns out that if we exit the guest due to a hcall instruction (sc 1),
and the loading of the instruction in the guest exit path fails for any
reason, the call to kvmppc_ld() in kvmppc_get_last_inst() fetches the
instruction after the hcall instruction rather than the hcall itself.
This in turn means that the instruction doesn't get recognized as an
hcall in kvmppc_handle_exit_pr() but gets passed to the guest kernel
as a sc instruction. That usually results in the guest kernel getting
a return code of 38 (ENOSYS) from an hcall, which often triggers a
BUG_ON() or other failure.
This fixes the problem by adding a new variant of kvmppc_get_last_inst()
called kvmppc_get_last_sc(), which fetches the instruction if necessary
from pc - 4 rather than pc.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
-rw-r--r-- | arch/powerpc/include/asm/kvm_book3s.h | 38 | ||||
-rw-r--r-- | arch/powerpc/kvm/book3s_pr.c | 2 |
2 files changed, 39 insertions, 1 deletions
diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h index 08891d07aeb6..fa19e2f1a874 100644 --- a/arch/powerpc/include/asm/kvm_book3s.h +++ b/arch/powerpc/include/asm/kvm_book3s.h @@ -334,6 +334,27 @@ static inline u32 kvmppc_get_last_inst(struct kvm_vcpu *vcpu) return r; } +/* + * Like kvmppc_get_last_inst(), but for fetching a sc instruction. + * Because the sc instruction sets SRR0 to point to the following + * instruction, we have to fetch from pc - 4. + */ +static inline u32 kvmppc_get_last_sc(struct kvm_vcpu *vcpu) +{ + ulong pc = kvmppc_get_pc(vcpu) - 4; + struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu); + u32 r; + + /* Load the instruction manually if it failed to do so in the + * exit path */ + if (svcpu->last_inst == KVM_INST_FETCH_FAILED) + kvmppc_ld(vcpu, &pc, sizeof(u32), &svcpu->last_inst, false); + + r = svcpu->last_inst; + svcpu_put(svcpu); + return r; +} + static inline ulong kvmppc_get_fault_dar(struct kvm_vcpu *vcpu) { struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu); @@ -446,6 +467,23 @@ static inline u32 kvmppc_get_last_inst(struct kvm_vcpu *vcpu) return vcpu->arch.last_inst; } +/* + * Like kvmppc_get_last_inst(), but for fetching a sc instruction. + * Because the sc instruction sets SRR0 to point to the following + * instruction, we have to fetch from pc - 4. + */ +static inline u32 kvmppc_get_last_sc(struct kvm_vcpu *vcpu) +{ + ulong pc = kvmppc_get_pc(vcpu) - 4; + + /* Load the instruction manually if it failed to do so in the + * exit path */ + if (vcpu->arch.last_inst == KVM_INST_FETCH_FAILED) + kvmppc_ld(vcpu, &pc, sizeof(u32), &vcpu->arch.last_inst, false); + + return vcpu->arch.last_inst; +} + static inline ulong kvmppc_get_fault_dar(struct kvm_vcpu *vcpu) { return vcpu->arch.fault_dar; diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c index 983e5eda892f..27db1e665959 100644 --- a/arch/powerpc/kvm/book3s_pr.c +++ b/arch/powerpc/kvm/book3s_pr.c @@ -792,7 +792,7 @@ program_interrupt: } case BOOK3S_INTERRUPT_SYSCALL: if (vcpu->arch.papr_enabled && - (kvmppc_get_last_inst(vcpu) == 0x44000022) && + (kvmppc_get_last_sc(vcpu) == 0x44000022) && !(vcpu->arch.shared->msr & MSR_PR)) { /* SC 1 papr hypercalls */ ulong cmd = kvmppc_get_gpr(vcpu, 3); |