On Thu, 17 May 2018 16:33:13 +1000
Paul Mackerras <paulus@xxxxxxxxxx> wrote:
> On Fri, Apr 06, 2018 at 02:14:09PM +1000, Nicholas Piggin wrote:
> > It's possible to take a SRESET or MCE in these paths due to a bug
> > in the host code or a NMI IPI etc. A recent bug attempting to load
> > a virtual address gave a complete but cryptic error, abridged:
> >
> > Oops: Bad interrupt in KVM entry/exit code, sig: 6 [#1]
> > LE SMP NR_CPUS=2048 NUMA PowerNV
> > CPU: 53 PID: 6582 Comm: qemu-system-ppc Not tainted
> > NIP: c0000000000155ac LR: c0000000000c2430 CTR:
> > c000000000015580 REGS: c000000fff76dd80 TRAP: 0200 Not tainted
> > MSR: 9000000000201003 <SF,HV,ME,RI,LE> CR: 48082222 XER:
> > 00000000 CFAR: 0000000102900ef0 DAR: d00017fffd941a28 DSISR:
> > 00000040 SOFTE: 3 NIP [c0000000000155ac] perf_trace_tlbie+0x2c/0x1a0
> > LR [c0000000000c2430] do_tlbies+0x230/0x2f0
> >
> > Sending NMIs through the Linux handlers gives a nicer output:
> >
> > Severe Machine check interrupt [Not recovered]
> > NIP [c0000000000155ac]: perf_trace_tlbie+0x2c/0x1a0
> > Initiator: CPU
> > Error type: Real address [Load (bad)]
> > Effective address: d00017fffcc01a28
> > opal: Machine check interrupt unrecoverable: MSR(RI=0)
> > opal: Hardware platform error: Unrecoverable Machine Check
> > exception CPU: 0 PID: 6700 Comm: qemu-system-ppc Tainted: G M
> > NIP: c0000000000155ac LR: c0000000000c23c0 CTR:
> > c000000000015580 REGS: c000000fff9e9d80 TRAP: 0200 Tainted: G M
> > MSR: 9000000000201001 <SF,HV,ME,LE> CR: 48082222 XER:
> > 00000000 CFAR: 000000010cbc1a30 DAR: d00017fffcc01a28 DSISR:
> > 00000040 SOFTE: 3 NIP [c0000000000155ac] perf_trace_tlbie+0x2c/0x1a0
> > LR [c0000000000c23c0] do_tlbies+0x1c0/0x280
> >
> > Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
> > ---
> > This is lightly tested only, not sure if there would be a better way
> > to do it?
>
> The patch seems reasonable. I have just one comment below. Do you
> want to re-send it without the RFC tag, or should I just take it?
I can re-send if you'd like an updated changelog and comment
for that MSR_RI bit.
>
> > arch/powerpc/kvm/book3s_hv_builtin.c | 12 ++++++++++++
> > 1 file changed, 12 insertions(+)
> >
> > diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c
> > b/arch/powerpc/kvm/book3s_hv_builtin.c index
> > de18299f92b7..0b9b8e188bfa 100644 ---
> > a/arch/powerpc/kvm/book3s_hv_builtin.c +++
> > b/arch/powerpc/kvm/book3s_hv_builtin.c @@ -18,6 +18,7 @@
> > #include <linux/cma.h>
> > #include <linux/bitops.h>
> >
> > +#include <asm/asm-prototypes.h>
> > #include <asm/cputable.h>
> > #include <asm/kvm_ppc.h>
> > #include <asm/kvm_book3s.h>
> > @@ -633,6 +634,17 @@ int kvmppc_rm_h_eoi(struct kvm_vcpu *vcpu,
> > unsigned long xirr)
> > void kvmppc_bad_interrupt(struct pt_regs *regs)
> > {
> > + regs->msr &= ~MSR_RI;
>
> This is worth mentioning in the commit message. I assume you're doing
> it to make sure we won't try to continue execution under any
> circumstances?
That's right, sure I'll mention it. Probably a comment here wouldn't
hurt either.
Thanks,
Nick
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