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Re: [PATCH v4 08/12] xen/physinfo: encode Arm SVE vector length in arch_capabilities
- To: Jan Beulich <jbeulich@xxxxxxxx>
- From: Luca Fancellu <Luca.Fancellu@xxxxxxx>
- Date: Thu, 30 Mar 2023 10:41:35 +0000
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- Cc: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>, Wei Chen <Wei.Chen@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Thu, 30 Mar 2023 10:41:57 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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- Thread-topic: [PATCH v4 08/12] xen/physinfo: encode Arm SVE vector length in arch_capabilities
> On 28 Mar 2023, at 11:14, Jan Beulich <jbeulich@xxxxxxxx> wrote:
>
> On 27.03.2023 12:59, Luca Fancellu wrote:
>> --- a/xen/arch/arm/arm64/sve.c
>> +++ b/xen/arch/arm/arm64/sve.c
>> @@ -124,3 +124,15 @@ int __init sve_parse_dom0_param(const char *str_begin,
>> const char *str_end)
>> {
>> return parse_integer("sve", str_begin, str_end, (int*)&opt_dom0_sve);
>> }
>> +
>> +void sve_arch_cap_physinfo(uint32_t *arch_capabilities)
>> +{
>> + if ( cpu_has_sve )
>> + {
>> + /* Vector length is divided by 128 to save some space */
>> + uint32_t sve_vl = MASK_INSR(sve_encode_vl(get_sys_vl_len()),
>> + XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK);
>> +
>> + *arch_capabilities |= sve_vl;
>> + }
>> +}
>
> I'm again wondering why a separate function is needed, when everything
> that's needed is ...
>
>> --- a/xen/arch/arm/sysctl.c
>> +++ b/xen/arch/arm/sysctl.c
>> @@ -11,11 +11,14 @@
>> #include <xen/lib.h>
>> #include <xen/errno.h>
>> #include <xen/hypercall.h>
>> +#include <asm/arm64/sve.h>
>
> ... becoming available here for use ...
>
>> #include <public/sysctl.h>
>>
>> void arch_do_physinfo(struct xen_sysctl_physinfo *pi)
>> {
>> pi->capabilities |= XEN_SYSCTL_PHYSCAP_hvm | XEN_SYSCTL_PHYSCAP_hap;
>> +
>> + sve_arch_cap_physinfo(&pi->arch_capabilities);
>
> ... here. That would be even more so if, like suggested before,
> get_sys_vl_len() returned 0 when !cpu_has_sve.
I’ve had a look on this, I can do everything In arch_do_physinfo if in
xen/include/public/sysctl.h
the XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK is protected by __aarch64__ or __arm__ .
Do you agree on that?
>
> Jan
|
