[PATCH v5 18/18] kvm: arm64: Allow tuning the physical address size for VM

Suzuki K Poulose Suzuki.Poulose at arm.com
Mon Sep 17 07:43:53 PDT 2018


Hi Peter,

On 17/09/2018 15:20, Peter Maydell wrote:
> On 17 September 2018 at 11:41, Suzuki K Poulose <suzuki.poulose at arm.com> wrote:
>> Allow specifying the physical address size limit for a new
>> VM via the kvm_type argument for the KVM_CREATE_VM ioctl. This
>> allows us to finalise the stage2 page table as early as possible
>> and hence perform the right checks on the memory slots
>> without complication. The size is ecnoded as Log2(PA_Size) in
>> bits[7:0] of the type field. For backward compatibility the
>> value 0 is reserved and implies 40bits. Also, lift the limit
>> of the IPA to host limit and allow lower IPA sizes (e.g, 32).
>>
>> The userspace could check the extension KVM_CAP_ARM_VM_PHYS_SHIFT
>> for the availability of this feature. The cap check returns the
>> maximum limit for the physical address shift supported by the host.
>>
>> Cc: Marc Zyngier <marc.zyngier at arm.com>
>> Cc: Christoffer Dall <cdall at kernel.org>
>> Cc: Peter Maydel <peter.maydell at linaro.org>
> 
> Typo: my surname has two "l"s in it.

Sorry about that. I have fixed this locally. Btw, did you get
a chance to look at the patch itself ? If you did, are you fine
with the API ?

Suzuki




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