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Re: [PATCH 02/14] x86/xstate: Create map/unmap primitives for xsave areas
- To: Alejandro Vallejo <alejandro.vallejo@xxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Tue, 29 Oct 2024 09:19:31 +0100
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Tue, 29 Oct 2024 08:19:40 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 28.10.2024 16:49, Alejandro Vallejo wrote:
> --- a/xen/arch/x86/include/asm/xstate.h
> +++ b/xen/arch/x86/include/asm/xstate.h
> @@ -143,4 +143,24 @@ static inline bool xstate_all(const struct vcpu *v)
> (v->arch.xcr0_accum & XSTATE_LAZY & ~XSTATE_FP_SSE);
> }
>
> +/*
> + * Fetch a pointer to the XSAVE area of a vCPU
> + *
> + * If ASI is enabled for the domain, this mapping is pCPU-local.
Taking the umap commentary into account, I think this needs to expand
some, to also symmetrically cover what the unmap comment says regarding
"v is [not] the currently scheduled vCPU". This may then also help
better see the further outlook, as Andrew was asking for.
> + * @param v Owner of the XSAVE area
> + */
> +#define vcpu_map_xsave_area(v) ((v)->arch.xsave_area)
> +
> +/*
> + * Drops the XSAVE area of a vCPU and nullifies its pointer on exit.
Nit: I expect it drops the mapping, not the area.
> + * If ASI is enabled and v is not the currently scheduled vCPU then the
> + * per-pCPU mapping is removed from the address space.
> + *
> + * @param v vCPU logically owning xsave_area
> + * @param xsave_area XSAVE blob of v
> + */
> +#define vcpu_unmap_xsave_area(v, x) ({ (x) = NULL; })
> +
> #endif /* __ASM_XSTATE_H */
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