Re: [Xen-devel] [PATCH 2/4] x86/hypervisor: pass flags to hypervisor_flush_tlb

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Feb 12, 2020 at 04:09:16PM +0000, Wei Liu wrote:
> Hyper-V's L0 assisted flush has fine-grained control over what gets
> flushed. We need all the flags available to make the best decisions
> possible.
> 
> No functional change because Xen's implementation doesn't care about
> what is passed to it.

While it's certainly fine to pass a flags field with more information,
the flush flags for Xen can also contain FLUSH_CACHE, FLUSH_VCPU_STATE
or FLUSH_ROOT_PGTBL, can you add an assert that those never get passed
to the flush hook?

IMO we should define a mask with FLUSH_TLB, FLUSH_TLB_GLOBAL,
FLUSH_VA_VALID and FLUSH_ORDER_MASK and assert that those are the only
valid flags to be used for the hypervisor assisted flush hook.

Thanks, Roger.

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