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Date:   Tue, 18 Oct 2022 16:40:11 +0000
From:   Quentin Perret <qperret@google.com>
To:     Will Deacon <will@kernel.org>
Cc:     kvmarm@lists.linux.dev, Sean Christopherson <seanjc@google.com>,
        Vincent Donnefort <vdonnefort@google.com>,
        Alexandru Elisei <alexandru.elisei@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        James Morse <james.morse@arm.com>,
        Chao Peng <chao.p.peng@linux.intel.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Fuad Tabba <tabba@google.com>,
        Oliver Upton <oliver.upton@linux.dev>,
        Marc Zyngier <maz@kernel.org>, kernel-team@android.com,
        kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 12/25] KVM: arm64: Add infrastructure to create and
 track pKVM instances at EL2
Message-ID: <Y07W63YlwZ6yClOi@google.com>
References: <20221017115209.2099-1-will@kernel.org>
 <20221017115209.2099-13-will@kernel.org>
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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()?