linux-kernel - Re: [PATCH 1/2] kvm: arm: Clean up the checking for huge mapping

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Date:   Thu, 11 Apr 2019 09:48:33 +0800
From:   Zenghui Yu <yuzenghui@...wei.com>
To:     Suzuki K Poulose <suzuki.poulose@....com>,
        <linux-arm-kernel@...ts.infradead.org>
CC:     <linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>,
        <kvmarm@...ts.cs.columbia.edu>, <julien.thierry@....com>,
        <christoffer.dall@....com>, <marc.zyngier@....com>,
        <andrew.murray@....com>, <eric.auger@...hat.com>,
        <zhengxiang9@...wei.com>, <wanghaibin.wang@...wei.com>
Subject: Re: [PATCH 1/2] kvm: arm: Clean up the checking for huge mapping


On 2019/4/10 23:23, Suzuki K Poulose wrote:
> If we are checking whether the stage2 can map PAGE_SIZE,
> we don't have to do the boundary checks as both the host
> VMA and the guest memslots are page aligned. Bail the case
> easily.
> 
> Cc: Christoffer Dall <christoffer.dall@....com>
> Cc: Marc Zyngier <marc.zyngier@....com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
> ---
>   virt/kvm/arm/mmu.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
> index a39dcfd..6d73322 100644
> --- a/virt/kvm/arm/mmu.c
> +++ b/virt/kvm/arm/mmu.c
> @@ -1624,6 +1624,10 @@ static bool fault_supports_stage2_huge_mapping(struct kvm_memory_slot *memslot,
>   	hva_t uaddr_start, uaddr_end;
>   	size_t size;
>   
> +	/* The memslot and the VMA are guaranteed to be aligned to PAGE_SIZE */
> +	if (map_size == PAGE_SIZE)
> +		return true;
> +
>   	size = memslot->npages * PAGE_SIZE;
>   
>   	gpa_start = memslot->base_gfn << PAGE_SHIFT;
> 
We can do a comment clean up as well in this patch.

s/<< PAGE_SIZE/<< PAGE_SHIFT/


thanks,
zenghui