[PATCH] arm/arm64: KVM: relax the requirements of VMA alignment for THP

Marc Zyngier marc.zyngier at arm.com
Fri Dec 13 12:27:10 EST 2013

On 13/12/13 17:20, Christoffer Dall wrote:
> On Fri, Dec 13, 2013 at 04:56:06PM +0000, Marc Zyngier wrote:
>> The THP code in KVM/ARM is a bit restrictive in not allowing a THP
>> to be used if the VMA is not 2MB aligned. Actually, it is not so much
>> the VMA that matters, but the associated memslot:
>> A process can perfectly mmap a region with no particular alignment
>> restriction, and then pass a 2MB aligned address to KVM. In this
>> case, KVM will only use this 2MB aligned region, and will ignore
>> the range between vma->vm_start and memslot->userspace_addr.
>> It can also choose to place this memslot at whatever alignment it
>> wants in the IPA space. In the end, what matters is the relative
>> alignment of the user space and IPA mappings with respect to a
>> 2M page. They absolutely must be the same if you want to use THP.
> Looks good to me:
> Acked-by: Christoffer Dall <christoffer.dall at linaro.org>

Thanks for the review!

Jazz is not dead. It just smells funny...

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