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SubjectRe: [PATCH v2 6/8] KVM: Fix multiple races in gfn=>pfn cache refresh
On Wed, Apr 27, 2022 at 7:16 PM Sean Christopherson <seanjc@google.com> wrote:

> @@ -159,10 +249,23 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
>

The following code of refresh_in_progress is somewhat like mutex.

+ mutex_lock(&gpc->refresh_in_progress); // before write_lock_irq(&gpc->lock);

Is it fit for the intention?

Thanks
Lai

> write_lock_irq(&gpc->lock);
>
> + /*
> + * If another task is refreshing the cache, wait for it to complete.
> + * There is no guarantee that concurrent refreshes will see the same
> + * gpa, memslots generation, etc..., so they must be fully serialized.
> + */
> + while (gpc->refresh_in_progress) {
> + write_unlock_irq(&gpc->lock);
> +
> + cond_resched();
> +
> + write_lock_irq(&gpc->lock);
> + }
> + gpc->refresh_in_progress = true;
> +
> old_pfn = gpc->pfn;
> old_khva = gpc->khva - offset_in_page(gpc->khva);
> old_uhva = gpc->uhva;
> - old_valid = gpc->valid;
>

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