On 03/23/2012 02:23 AM, Rusty Russell wrote:
> On Mon, 12 Mar 2012 02:52:41 -0400, Christoffer Dall <c.dall@xxxxxxxxxxxxxxxxxxxxxx> wrote:
> > @@ -236,6 +237,24 @@ int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
> >
> > int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
> > {
> > + unsigned long cpsr;
> > + unsigned long sctlr;
> > +
> > +
> > + /* Init execution CPSR */
> > + asm volatile ("mrs %[cpsr], cpsr" :
> > + [cpsr] "=r" (cpsr));
> > + vcpu->arch.regs.cpsr = SVC_MODE | PSR_I_BIT | PSR_F_BIT | PSR_A_BIT |
> > + (cpsr & PSR_E_BIT);
> > +
> > + /* Init SCTLR with MMU disabled */
> > + asm volatile ("mrc p15, 0, %[sctlr], c1, c0, 0" :
> > + [sctlr] "=r" (sctlr));
> > + vcpu->arch.cp15[c1_SCTLR] = sctlr & ~1U;
> > +
> > + /* Compute guest MPIDR */
> > + vcpu->arch.cp15[c0_MPIDR] = (read_cpuid_mpidr() & ~0xff)
> > + | vcpu->vcpu_id;
> > return 0;
> > }
>
> Hi Christoffer!
>
> I started cleaning this up, on the theory that we should use the
> defined reset values rather than basing them on host values. Then I
> discovered that this is ignored by qemu anyway, which overrides the
> values (except for MPIDR: I set that to 0x80000000 | vcpu->vcpu_id,
> which seems correct to me).
>
> Should this code be dropped altogether? Peter points out that once we
> add new regs, they *must* be initialized to correct reset values in case
> older QEMU knows nothing about them, but for the rest it just seems
> confusing...
>
It's best to initialize everything. As far as this code is concerned
qemu is just another user and we shouldn't rely on its implementation.
--
error compiling committee.c: too many arguments to function
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