[PATCH v4 12/25] KVM: arm64: Add infrastructure to create and track pKVM instances at EL2

[Quentin Perret]

On Monday 17 Oct 2022 at 12:51:56 (+0100), Will Deacon wrote:
> +static void *map_donated_memory_noclear(unsigned long host_va, size_t size)
> +{
> +	void *va = (void *)kern_hyp_va(host_va);
> +
> +	if (!PAGE_ALIGNED(va))
> +		return NULL;
> +
> +	if (__pkvm_host_donate_hyp(hyp_virt_to_pfn(va),
> +				   PAGE_ALIGN(size) >> PAGE_SHIFT))
> +		return NULL;
> +
> +	return va;
> +}
> +
> +static void *map_donated_memory(unsigned long host_va, size_t size)
> +{
> +	void *va = map_donated_memory_noclear(host_va, size);
> +
> +	if (va)
> +		memset(va, 0, size);
> +
> +	return va;
> +}
> +
> +static void __unmap_donated_memory(void *va, size_t size)
> +{
> +	WARN_ON(__pkvm_hyp_donate_host(hyp_virt_to_pfn(va),
> +				       PAGE_ALIGN(size) >> PAGE_SHIFT));
> +}
> +
> +static void unmap_donated_memory(void *va, size_t size)
> +{
> +	if (!va)
> +		return;
> +
> +	memset(va, 0, size);
> +	__unmap_donated_memory(va, size);
> +}
> +
> +static void unmap_donated_memory_noclear(void *va, size_t size)
> +{
> +	if (!va)
> +		return;
> +
> +	__unmap_donated_memory(va, size);
> +}

Nit: I'm not a huge fan of the naming here, these do more than just
map/unmap random pages. This only works for host pages, the donation
path has permission checks, etc. Maybe {admit,return}_host_memory()?