Re: [Xen-devel] RFC: PVH set vcpu info context in vmcs....

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 13.08.13 at 03:45, Mukesh Rathor <mukesh.rathor@xxxxxxxxxx> wrote:
> int vmx_pvh_set_vcpu_info(struct vcpu *v, struct vcpu_guest_context *ctxtp)
> {
>     int rc;
> 
>     if ( v->vcpu_id == 0 )
>         return 0;

Bogus/pointless.

>     if ( !(ctxtp->flags & VGCF_in_kernel) )
>         return -EINVAL;
> 
>     if ( ctxtp->ldt_base || ctxtp->ldt_ents ||
>          (ctxtp->user_regs.cs & 4) || ctxtp->user_regs.ss || 
>          ctxtp->user_regs.es || ctxtp->user_regs.ds )
>         return -EINVAL;

How about FS/GS? If you don't enforce these selectors to be zero
too, then loading only base and selector values below isn't
sufficient (and again potentially inconsistent).

> 
>     if ( ctxtp->user_regs.cs == 0 )
>         return -EINVAL;

Perhaps also check RPL == 0?

>     vmx_vmcs_enter(v);
>     __vmwrite(GUEST_GDTR_BASE, ctxtp->gdt.pvh.addr);
>     __vmwrite(GUEST_GDTR_LIMIT, ctxtp->gdt.pvh.limit);
> 
>     __vmwrite(GUEST_FS_BASE, ctxtp->fs_base);
>     __vmwrite(GUEST_GS_BASE, ctxtp->gs_base_kernel);
> 
>     /* IA-32e: ss/es/ds are ignored, we load cs only. */ 
>     __vmwrite(GUEST_CS_SELECTOR, ctxtp->user_regs.cs);
>     if ( (rc = hvm_load_segment_selector(x86_seg_cs, ctxtp->user_regs.cs)) ) 
>         return rc;

You can't use that function here without modification, as it
assumes v == current.

Jan

> 
>     __vmwrite(GUEST_FS_SELECTOR, ctxtp->user_regs.fs);
>     __vmwrite(GUEST_GS_SELECTOR, ctxtp->user_regs.gs);
> 
>     if ( (rc = vmx_add_guest_msr(MSR_SHADOW_GS_BASE)) )
>     {
>         vmx_vmcs_exit(v);
>         return rc;
>     }
>     vmx_write_guest_msr(MSR_SHADOW_GS_BASE, ctxtp->gs_base_user);
> 
>     vmx_vmcs_exit(v);
>     return 0;
> }




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