Re: [Xen-devel] [PATCH v14 06/11] x86/hvm: Introduce hvm_save_mtrr_msr_one func

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.07.18 at 14:14, <aisaila@xxxxxxxxxxxxxxx> wrote:
> This is used to save data from a single instance.
> 
> Signed-off-by: Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx>
> 
> ---
> Changes since v11:
>       - hvm_save_mtrr_msr() now returns err from hvm_save_mtrr_msr_one().
> 
> Note: This patch is based on Roger Pau Monne's series[1]
> ---
>  xen/arch/x86/hvm/mtrr.c | 81 
> +++++++++++++++++++++++++++----------------------
>  1 file changed, 44 insertions(+), 37 deletions(-)
> 
> diff --git a/xen/arch/x86/hvm/mtrr.c b/xen/arch/x86/hvm/mtrr.c
> index 48facbb..47a5c29 100644
> --- a/xen/arch/x86/hvm/mtrr.c
> +++ b/xen/arch/x86/hvm/mtrr.c
> @@ -718,52 +718,59 @@ int hvm_set_mem_pinned_cacheattr(struct domain *d, 
> uint64_t gfn_start,
>      return 0;
>  }
>  
> -static int hvm_save_mtrr_msr(struct domain *d, hvm_domain_context_t *h)
> +static int hvm_save_mtrr_msr_one(struct vcpu *v, hvm_domain_context_t *h)
>  {
> -    struct vcpu *v;
> +    const struct mtrr_state *mtrr_state = &v->arch.hvm_vcpu.mtrr;
> +    struct hvm_hw_mtrr hw_mtrr = {
> +        .msr_mtrr_def_type = mtrr_state->def_type |
> +                             MASK_INSR(mtrr_state->fixed_enabled,
> +                                       MTRRdefType_FE) |
> +                             MASK_INSR(mtrr_state->enabled, MTRRdefType_E),
> +        .msr_mtrr_cap      = mtrr_state->mtrr_cap,
> +    };
> +    unsigned int i;
>  
> -    /* save mtrr&pat */
> -    for_each_vcpu(d, v)
> +    if ( MASK_EXTR(hw_mtrr.msr_mtrr_cap, MTRRcap_VCNT) >
> +         (ARRAY_SIZE(hw_mtrr.msr_mtrr_var) / 2) )
>      {
> -        const struct mtrr_state *mtrr_state = &v->arch.hvm_vcpu.mtrr;
> -        struct hvm_hw_mtrr hw_mtrr = {
> -            .msr_mtrr_def_type = mtrr_state->def_type |
> -                                 MASK_INSR(mtrr_state->fixed_enabled,
> -                                           MTRRdefType_FE) |
> -                                 MASK_INSR(mtrr_state->enabled, 
> MTRRdefType_E),
> -            .msr_mtrr_cap      = mtrr_state->mtrr_cap,
> -        };
> -        unsigned int i;
> +        dprintk(XENLOG_G_ERR,
> +                "HVM save: %pv: too many (%lu) variable range MTRRs\n",
> +                v, MASK_EXTR(hw_mtrr.msr_mtrr_cap, MTRRcap_VCNT));
> +        return -EINVAL;
> +    }
>  
> -        if ( MASK_EXTR(hw_mtrr.msr_mtrr_cap, MTRRcap_VCNT) >
> -             (ARRAY_SIZE(hw_mtrr.msr_mtrr_var) / 2) )
> -        {
> -            dprintk(XENLOG_G_ERR,
> -                    "HVM save: %pv: too many (%lu) variable range MTRRs\n",
> -                    v, MASK_EXTR(hw_mtrr.msr_mtrr_cap, MTRRcap_VCNT));
> -            return -EINVAL;
> -        }
> +    hvm_get_guest_pat(v, &hw_mtrr.msr_pat_cr);
>  
> -        hvm_get_guest_pat(v, &hw_mtrr.msr_pat_cr);
> +    for ( i = 0; i < MASK_EXTR(hw_mtrr.msr_mtrr_cap, MTRRcap_VCNT); i++ )
> +    {
> +        /* save physbase */
> +        hw_mtrr.msr_mtrr_var[i*2] =
> +            ((uint64_t*)mtrr_state->var_ranges)[i*2];
> +        /* save physmask */
> +        hw_mtrr.msr_mtrr_var[i*2+1] =
> +            ((uint64_t*)mtrr_state->var_ranges)[i*2+1];
> +    }

As you move/re-indent code, please fix obvious style violations
(here: missing blanks around binary operators). It also would be
really nice if you got rid of the ugly and risky casts, and used
the actual structure fields instead.

> -        for ( i = 0; i < MASK_EXTR(hw_mtrr.msr_mtrr_cap, MTRRcap_VCNT); i++ )
> -        {
> -            /* save physbase */
> -            hw_mtrr.msr_mtrr_var[i*2] =
> -                ((uint64_t*)mtrr_state->var_ranges)[i*2];
> -            /* save physmask */
> -            hw_mtrr.msr_mtrr_var[i*2+1] =
> -                ((uint64_t*)mtrr_state->var_ranges)[i*2+1];
> -        }
> +    for ( i = 0; i < NUM_FIXED_MSR; i++ )
> +        hw_mtrr.msr_mtrr_fixed[i] =
> +            ((uint64_t*)mtrr_state->fixed_ranges)[i];

Whereas here I think you would best simply use memcpy(), again
to get rid of the cast.

Jan



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