Re: [Xen-devel] [PATCH RFC 08/12] xen/x86: setup PVHv2 Dom0 CPUs

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

On Mon, Sep 26, 2016 at 10:19:04AM -0600, Jan Beulich wrote:
> >>> On 29.07.16 at 18:29, <roger.pau@xxxxxxxxxx> wrote:
> > Initialize Dom0 BSP/APs and setup the memory and IO permissions.
> > 
> > Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> > ---
> > Cc: Jan Beulich <jbeulich@xxxxxxxx>
> > Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> > ---
> > The logic used to setup the CPUID leaves is extremely simplistic (and
> > probably wrong for hardware different than mine). I'm not sure what's the
> > best way to deal with this, the code that currently sets the CPUID leaves
> > for HVM guests lives in libxc, maybe moving it xen/common would be better?
> 
> Why don't you just set them from their respective hardware values?

That's what I'm already doing in this patch, but I'm not sure what should be 
removed (at least virt extensions should be removed, but I guess there's 
other stuff that we might want to remove too).
 
> > +static int __init hvm_setup_cpus(struct domain *d, paddr_t entry,
> > +                                 paddr_t start_info)
> > +{
> > +    vcpu_hvm_context_t cpu_ctx;
> > +    struct vcpu *v = d->vcpu[0];
> > +    int cpu, i, rc;
> > +    struct {
> > +        uint32_t index;
> > +        uint32_t count;
> > +    } cpuid_leaves[] = {
> > +        {0, XEN_CPUID_INPUT_UNUSED},
> > +        {1, XEN_CPUID_INPUT_UNUSED},
> > +        {2, XEN_CPUID_INPUT_UNUSED},
> > +        {4, 0},
> > +        {4, 1},
> > +        {4, 2},
> > +        {4, 3},
> > +        {4, 4},
> > +        {7, 0},
> > +        {0xa, XEN_CPUID_INPUT_UNUSED},
> > +        {0xd, 0},
> > +        {0x80000000, XEN_CPUID_INPUT_UNUSED},
> > +        {0x80000001, XEN_CPUID_INPUT_UNUSED},
> > +        {0x80000002, XEN_CPUID_INPUT_UNUSED},
> > +        {0x80000003, XEN_CPUID_INPUT_UNUSED},
> > +        {0x80000004, XEN_CPUID_INPUT_UNUSED},
> > +        {0x80000005, XEN_CPUID_INPUT_UNUSED},
> > +        {0x80000006, XEN_CPUID_INPUT_UNUSED},
> > +        {0x80000007, XEN_CPUID_INPUT_UNUSED},
> > +        {0x80000008, XEN_CPUID_INPUT_UNUSED},
> > +    };
> > +
> > +    printk("** Setting up BSP/APs **\n");
> > +
> > +    cpu = v->processor;
> > +    for ( i = 1; i < d->max_vcpus; i++ )
> > +    {
> > +        cpu = cpumask_cycle(cpu, &dom0_cpus);
> > +        setup_dom0_vcpu(d, i, cpu);
> > +    }
> > +
> > +    memset(&cpu_ctx, 0, sizeof(cpu_ctx));
> > +
> > +    cpu_ctx.mode = VCPU_HVM_MODE_32B;
> > +
> > +    cpu_ctx.cpu_regs.x86_32.ebx = start_info;
> > +    cpu_ctx.cpu_regs.x86_32.eip = entry;
> > +    cpu_ctx.cpu_regs.x86_32.cr0 = X86_CR0_PE | X86_CR0_ET;
> > +
> > +    cpu_ctx.cpu_regs.x86_32.cs_limit = ~0u;
> > +    cpu_ctx.cpu_regs.x86_32.ds_limit = ~0u;
> > +    cpu_ctx.cpu_regs.x86_32.ss_limit = ~0u;
> > +    cpu_ctx.cpu_regs.x86_32.tr_limit = 0x67;
> > +    cpu_ctx.cpu_regs.x86_32.cs_ar = 0xc9b;
> > +    cpu_ctx.cpu_regs.x86_32.ds_ar = 0xc93;
> > +    cpu_ctx.cpu_regs.x86_32.ss_ar = 0xc93;
> > +    cpu_ctx.cpu_regs.x86_32.tr_ar = 0x8b;
> 
> Much of this should be power on state of a HVM vCPU anyway, so
> it's not immediately clear why all of this is needed.

Oh, since I couldn't find any reference to the power on state of a HVM 
vCPU I though it might be better to set it all here, so it's clear what's 
the state on power on.

Roger.

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