On 02/06/2023 5:08 pm, Alejandro Vallejo wrote:
> On Fri, Jun 02, 2023 at 03:22:20PM +0100, Andrew Cooper wrote:
>> Linux deals with this in verify_cpu() (early asm) along with a FMS check
>> protecting the access to MSR_MISC_ENABLE, rather than using rdmsr_safe()
>> and catching the #GP.
> On a
On Fri, Jun 02, 2023 at 03:22:20PM +0100, Andrew Cooper wrote:
> On 01/06/2023 6:43 pm, Alejandro Vallejo wrote:
> > diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
> > index 09bebf8635..8414266281 100644
> > --- a/xen/arch/x86/boot/head.S
> > +++ b/xen/arch/x86/boot/head.S
> > @@
On 01/06/2023 6:43 pm, Alejandro Vallejo wrote:
> diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
> index 09bebf8635..8414266281 100644
> --- a/xen/arch/x86/boot/head.S
> +++ b/xen/arch/x86/boot/head.S
> @@ -647,11 +653,18 @@ trampoline_setup:
> cpuid
> 1: mov
On 02.06.2023 14:05, Andrew Cooper wrote:
> On 01/06/2023 6:43 pm, Alejandro Vallejo wrote:
>> @@ -151,6 +152,11 @@ not_multiboot:
>> .Lnot_aligned:
>> add $sym_offs(.Lbag_alg_msg),%esi # Error message
>> jmp .Lget_vtb
>> +#if IS_ENABLED(CONFIG_REQUIRE_NX_BIT)
>
>
On 01/06/2023 6:43 pm, Alejandro Vallejo wrote:
> This allows replacing many instances of runtime checks with folded
> constants. The patch asserts support for the NX bit in PTEs at boot time
> and if so short-circuits cpu_has_nx to 1. This has several knock-on effects
> that improve codegen:
>
Hi,
Sure to everything. A couple of notes:
On Fri, Jun 02, 2023 at 10:31:08AM +0200, Jan Beulich wrote:
> > + def_bool n
> > + prompt "Require NX bit support"
>
> Just
>
> bool "Require NX bit support"
>
> please.
I didn't realize Kconfig defaulted to 'n'. That's neat, thanks.
>
>
On 02/06/2023 9:31 am, Jan Beulich wrote:
> On 01.06.2023 19:43, Alejandro Vallejo wrote:
>> This allows replacing many instances of runtime checks with folded
>> constants. The patch asserts support for the NX bit in PTEs at boot time
>> and if so short-circuits cpu_has_nx to 1. This has several
On 01.06.2023 19:43, Alejandro Vallejo wrote:
> This allows replacing many instances of runtime checks with folded
> constants. The patch asserts support for the NX bit in PTEs at boot time
> and if so short-circuits cpu_has_nx to 1. This has several knock-on effects
> that improve codegen:
> *
This allows replacing many instances of runtime checks with folded
constants. The patch asserts support for the NX bit in PTEs at boot time
and if so short-circuits cpu_has_nx to 1. This has several knock-on effects
that improve codegen:
* _PAGE_NX matches _PAGE_NX_BIT, optimising the macro to a
