[PATCH] ARM64: KVM: Fix coherent_icache_guest_page() for host with external L3-cache.
marc.zyngier at arm.com
Wed Aug 14 11:49:24 EDT 2013
On 2013-08-14 16:35, Peter Maydell wrote:
> On 14 August 2013 16:23, Marc Zyngier <marc.zyngier at arm.com> wrote:
>> On 2013-08-14 15:22, Anup Patel wrote:
>>> It seems a bit unnatural to have cache cleaning is user-space. I am
>>> other architectures don't have such cache cleaning in user-space
>> Well, we have it on AArch64. Why would we blindly nuke the whole
>> if we can do the right thing, efficiently, on the right range?
> When exactly would userspace have to care about the cache?
Only for the initial payload, I'd expect. Unless I've missed something
> This patch isn't exactly clear about the circumstances. I
> think you'd need a really strong reason for not dealing with
> this in the kernel -- in general userspace KVM tools don't
> otherwise have to deal with cache maintenance at all.
I believe we *could* do it in the kernel, just at the expense of a lot
more CPU cycles.
A possible alternative would be to use HCR.DC, but I need to have a
look and see what it breaks...
Fast, cheap, reliable. Pick two.
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