diff options
| author | Paul Mackerras <paulus@ozlabs.org> | 2018-03-07 22:17:20 +1100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-05-16 10:08:42 +0200 |
| commit | b87943f388ab24f66b4db380d47fe691a67dc44d (patch) | |
| tree | 30a8846656da63324f411efd813c17547ef8b1ec /arch | |
| parent | 57d641003679cf452f995b6f034b567d5d4e3be3 (diff) | |
KVM: PPC: Book3S HV: Fix trap number return from __kvmppc_vcore_entry
commit a8b48a4dccea77e29462e59f1dbf0d5aa1ff167c upstream.
This fixes a bug where the trap number that is returned by
__kvmppc_vcore_entry gets corrupted. The effect of the corruption
is that IPIs get ignored on POWER9 systems when the IPI is sent via
a doorbell interrupt to a CPU which is executing in a KVM guest.
The effect of the IPI being ignored is often that another CPU locks
up inside smp_call_function_many() (and if that CPU is holding a
spinlock, other CPUs then lock up inside raw_spin_lock()).
The trap number is currently held in register r12 for most of the
assembly-language part of the guest exit path. In that path, we
call kvmppc_subcore_exit_guest(), which is a C function, without
restoring r12 afterwards. Depending on the kernel config and the
compiler, it may modify r12 or it may not, so some config/compiler
combinations see the bug and others don't.
To fix this, we arrange for the trap number to be stored on the
stack from the 'guest_bypass:' label until the end of the function,
then the trap number is loaded and returned in r12 as before.
Cc: stable@vger.kernel.org # v4.8+
Fixes: fd7bacbca47a ("KVM: PPC: Book3S HV: Fix TB corruption in guest exit path on HMI interrupt")
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/kvm/book3s_hv_rmhandlers.S | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index 55fbc0c78721..79a180cf4c94 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -299,7 +299,6 @@ kvm_novcpu_exit: stw r12, STACK_SLOT_TRAP(r1) bl kvmhv_commence_exit nop - lwz r12, STACK_SLOT_TRAP(r1) b kvmhv_switch_to_host /* @@ -1023,6 +1022,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) secondary_too_late: li r12, 0 + stw r12, STACK_SLOT_TRAP(r1) cmpdi r4, 0 beq 11f stw r12, VCPU_TRAP(r4) @@ -1266,12 +1266,12 @@ mc_cont: bl kvmhv_accumulate_time #endif + stw r12, STACK_SLOT_TRAP(r1) mr r3, r12 /* Increment exit count, poke other threads to exit */ bl kvmhv_commence_exit nop ld r9, HSTATE_KVM_VCPU(r13) - lwz r12, VCPU_TRAP(r9) /* Stop others sending VCPU interrupts to this physical CPU */ li r0, -1 @@ -1549,6 +1549,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) * POWER7/POWER8 guest -> host partition switch code. * We don't have to lock against tlbies but we do * have to coordinate the hardware threads. + * Here STACK_SLOT_TRAP(r1) contains the trap number. */ kvmhv_switch_to_host: /* Secondary threads wait for primary to do partition switch */ @@ -1599,11 +1600,11 @@ BEGIN_FTR_SECTION END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) /* If HMI, call kvmppc_realmode_hmi_handler() */ + lwz r12, STACK_SLOT_TRAP(r1) cmpwi r12, BOOK3S_INTERRUPT_HMI bne 27f bl kvmppc_realmode_hmi_handler nop - li r12, BOOK3S_INTERRUPT_HMI /* * At this point kvmppc_realmode_hmi_handler would have resync-ed * the TB. Hence it is not required to subtract guest timebase @@ -1678,6 +1679,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) li r0, KVM_GUEST_MODE_NONE stb r0, HSTATE_IN_GUEST(r13) + lwz r12, STACK_SLOT_TRAP(r1) /* return trap # in r12 */ ld r0, SFS+PPC_LR_STKOFF(r1) addi r1, r1, SFS mtlr r0 |