Re: [Xen-devel] [PATCH v2 10/16] x86/PV: split out dealing with CRn from privileged instruction handling

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 28/09/16 09:14, Jan Beulich wrote:
> This is in preparation for using the generic emulator here.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>
> --- a/xen/arch/x86/traps.c
> +++ b/xen/arch/x86/traps.c
> @@ -2255,6 +2255,107 @@ unsigned long guest_to_host_gpr_switch(u
>  
>  void (*pv_post_outb_hook)(unsigned int port, u8 value);
>  
> +static int priv_op_read_cr(unsigned int reg, unsigned long *val,
> +                           struct x86_emulate_ctxt *ctxt)
> +{
> +    const struct vcpu *curr = current;
> +
> +    switch ( reg )
> +    {
> +    case 0: /* Read CR0 */
> +        *val = (read_cr0() & ~X86_CR0_TS) | curr->arch.pv_vcpu.ctrlreg[0];
> +        return X86EMUL_OKAY;
> +
> +    case 2: /* Read CR2 */
> +    case 4: /* Read CR4 */
> +        *val = curr->arch.pv_vcpu.ctrlreg[reg];
> +        return X86EMUL_OKAY;
> +
> +    case 3: /* Read CR3 */
> +    {
> +        const struct domain *currd = curr->domain;
> +        unsigned long mfn;

Any chance of switching this to mfn_t while you are moving it?

> +
> +        if ( !is_pv_32bit_domain(currd) )
> +        {
> +            mfn = pagetable_get_pfn(curr->arch.guest_table);
> +            *val = xen_pfn_to_cr3(mfn_to_gmfn(currd, mfn));
> +        }
> +        else
> +        {
> +            l4_pgentry_t *pl4e =
> +                
> map_domain_page(_mfn(pagetable_get_pfn(curr->arch.guest_table)));
> +
> +            mfn = l4e_get_pfn(*pl4e);
> +            unmap_domain_page(pl4e);
> +            *val = compat_pfn_to_cr3(mfn_to_gmfn(currd, mfn));
> +        }
> +        /* PTs should not be shared */
> +        BUG_ON(page_get_owner(mfn_to_page(mfn)) == dom_cow);
> +        return X86EMUL_OKAY;
> +    }
> +    }
> +
> +    return X86EMUL_UNHANDLEABLE;
> +}
> +
> +static int priv_op_write_cr(unsigned int reg, unsigned long val,
> +                            struct x86_emulate_ctxt *ctxt)
> +{
> +    struct vcpu *curr = current;
> +
> +    switch ( reg )
> +    {
> +    case 0: /* Write CR0 */
> +        if ( (val ^ read_cr0()) & ~X86_CR0_TS )
> +        {
> +            gdprintk(XENLOG_WARNING,
> +                    "Attempt to change unmodifiable CR0 flags\n");
> +            break;
> +        }
> +        do_fpu_taskswitch(!!(val & X86_CR0_TS));
> +        return X86EMUL_OKAY;
> +
> +    case 2: /* Write CR2 */
> +        curr->arch.pv_vcpu.ctrlreg[2] = val;
> +        arch_set_cr2(curr, val);
> +        return X86EMUL_OKAY;
> +
> +    case 3: /* Write CR3 */
> +    {
> +        struct domain *currd = curr->domain;
> +        unsigned long gfn;

Similarly, gfn_t ?

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

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