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Re: [PATCH v3 2/4] xen/arm: optimize the size of struct vcpu
- To: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- Date: Tue, 23 Dec 2025 12:37:49 +0000
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
- Delivery-date: Tue, 23 Dec 2025 12:37:57 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 22/12/2025 4:40 pm, Oleksii Kurochko wrote:
> When CONFIG_NEW_VGIC=y and CONFIG_ARM_64=y, the size of struct vcpu
> exceeds one page, which requires allocating two pages and led to the
> introduction of MAX_PAGES_PER_VCPU.
>
> To remove the need for MAX_PAGES_PER_VCPU in a follow-up patch, the vgic
> member of NEW_VGIC's struct vgic_vcpu member private_irq is changed to a
> pointer to struct vgic_irq.
> As a result, the size of struct vcpu for Arm64 is reduced to 2176 bytes,
> compared to 3840 bytes (without these changes and with CONFIG_ARM_64=y)
> and 4736 bytes (without these changes and with both CONFIG_ARM_64=y and
> CONFIG_NEW_VGIC=y).
>
> Since the private_irqs member is now a pointer, vcpu_vgic_init() and
> vcpu_vgic_free() are updated to allocate and free private_irqs instance.
>
> Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
Oh - even smaller than I was expecting.
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
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