Re: [Xen-devel] [PATCH 3/5] hvm/mtrr: copy hardware state for Dom0

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 10.05.18 at 19:15, <roger.pau@xxxxxxxxxx> wrote:
> Copy the state found on the hardware when creating a PVH Dom0. Since
> the memory map provided to a PVH Dom0 is based on the native one using
> the same set of MTRR ranges should provide Dom0 with a sane MTRR state
> without having to manually build it in Xen.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> ---
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
>  xen/arch/x86/hvm/mtrr.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/xen/arch/x86/hvm/mtrr.c b/xen/arch/x86/hvm/mtrr.c
> index 95a3deabea..1cb000388a 100644
> --- a/xen/arch/x86/hvm/mtrr.c
> +++ b/xen/arch/x86/hvm/mtrr.c
> @@ -176,6 +176,29 @@ int hvm_vcpu_cacheattr_init(struct vcpu *v)
>          ((uint64_t)PAT_TYPE_UC_MINUS << 48) |       /* PAT6: UC- */
>          ((uint64_t)PAT_TYPE_UNCACHABLE << 56);      /* PAT7: UC */
>  
> +    if ( is_hardware_domain(v->domain) )
> +    {
> +        /* Copy values from the host. */
> +        struct domain *d = v->domain;
> +        unsigned int i;
> +
> +        if ( mtrr_state.have_fixed )
> +            for ( i = 0; i < NUM_FIXED_MSR; i++ )
> +                mtrr_fix_range_msr_set(d, m, i,
> +                                      ((uint64_t 
> *)mtrr_state.fixed_ranges)[i]);

The presence/absence of fixed range MTRRs needs to be reflected in the
capabilities MSR. Strictly speaking in their absence MSR access attempts to
the fixed range MSRs should also cause #GP, as should any attempt to
enable them in defType.

> +        for ( i = 0; i < num_var_ranges; i++ )
> +        {
> +            mtrr_var_range_msr_set(d, m, MSR_IA32_MTRR_PHYSBASE(i),
> +                                   mtrr_state.var_ranges[i].base);
> +            mtrr_var_range_msr_set(d, m, MSR_IA32_MTRR_PHYSMASK(i),
> +                                   mtrr_state.var_ranges[i].mask);
> +        }
> +
> +        mtrr_def_type_msr_set(d, m, mtrr_state.def_type |
> +                                    (mtrr_state.enabled << 10));

In the interest of no further proliferation of this and similar literal numbers,
could I ask you to introduce #define-s into msr-index.h?

Jan


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