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Re: [qemu-s390x] [PATCH RFC] s390x/kvm: call cpu_synchronize_state() on
From: |
Cornelia Huck |
Subject: |
Re: [qemu-s390x] [PATCH RFC] s390x/kvm: call cpu_synchronize_state() on every kvm_arch_handle_exit() |
Date: |
Thu, 5 Apr 2018 10:03:46 +0200 |
On Thu, 5 Apr 2018 09:53:45 +0200
Christian Borntraeger <address@hidden> wrote:
> On 03/26/2018 11:20 AM, David Hildenbrand wrote:
> FWIW, I think your patch even fixes a bug:
>
> --- snip ----
> static int handle_diag(S390CPU *cpu, struct kvm_run *run, uint32_t ipb)
> {
> int r = 0;
> uint16_t func_code;
>
> /*
> * For any diagnose call we support, bits 48-63 of the resulting
> * address specify the function code; the remainder is ignored.
> */
> func_code = decode_basedisp_rs(&cpu->env, ipb, NULL) & DIAG_KVM_CODE_MASK;
>
> ---->
> static inline hwaddr decode_basedisp_s(CPUS390XState *env, uint32_t ipb,
> uint8_t *ar)
> {
> hwaddr addr = 0;
> uint8_t reg;
>
> reg = ipb >> 28;
> if (reg > 0) {
> addr = env->regs[reg];
>
> ----> we do the sync_regs after this in the diag handler!
> So currently we only handle the case with base reg == 0 correctly.
> So
> diag x,y,0x500(0)
> works
>
>
> but things like
> lghi 1,0x500
> diag x,y,0(1)
>
> not unless I miss something.
I think you are right.
>
>
> [...]
> > @@ -1778,6 +1760,8 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run
> > *run)
> >
> > qemu_mutex_lock_iothread();
> >
> > + cpu_synchronize_state(CPU(cpu));
> > +
> > switch (run->exit_reason) {
> > case KVM_EXIT_S390_SIEIC:
> > ret = handle_intercept(cpu);
> >
>
> Does it make sense to do this hunk NOW for 2.12 (cc stable)
> and queue your full patch for 2.13?
>
I'd prefer a cpu_synchronize_state() at the start of handle_diag() and
a respin of this patch for 2.13, but that should be fine as well.
I'll queue a proper patch for 2.12-rc.