linux-kernel - Re: [PATCH v5 17/43] arm64: RME: Allow VMM to set RIPAS

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Message-ID: <yq5afroec9jz.fsf@kernel.org>
Date: Wed, 30 Oct 2024 13:22:00 +0530
From: Aneesh Kumar K.V <aneesh.kumar@...nel.org>
To: Suzuki K Poulose <suzuki.poulose@....com>,
	Steven Price <steven.price@....com>, kvm@...r.kernel.org,
	kvmarm@...ts.linux.dev
Cc: Catalin Marinas <catalin.marinas@....com>,
	Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>,
	James Morse <james.morse@....com>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Zenghui Yu <yuzenghui@...wei.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Joey Gouly <joey.gouly@....com>,
	Alexandru Elisei <alexandru.elisei@....com>,
	Christoffer Dall <christoffer.dall@....com>,
	Fuad Tabba <tabba@...gle.com>, linux-coco@...ts.linux.dev,
	Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>,
	Gavin Shan <gshan@...hat.com>,
	Shanker Donthineni <sdonthineni@...dia.com>,
	Alper Gun <alpergun@...gle.com>
Subject: Re: [PATCH v5 17/43] arm64: RME: Allow VMM to set RIPAS

Suzuki K Poulose <suzuki.poulose@....com> writes:

> Hi Steven
>
>
>> +	if (WARN_ON(rmi_granule_undelegate(phys))) {
>> +		/* Undelegate failed: leak the page */
>> +		return;
>> +	}
>> +
>> +	free_page((unsigned long)phys_to_virt(phys));
>
> The above pattern of undelegate and reclaim a granule or leak appears 
> elsewhere in the KVM support code. Is it worth having a common helper to
> do the same ?
>
> something like: reclaim_delegated_granule()
>

free_delegated_page() which should really be renamed to
free_delegated_granule() essentially does that.

IMHO we should convert all the delgated allocation and free to
alloc_delegated_granule() and free_delegated_granule(). This will also
help in switching to a slab for granule allocation. 

>
>
>> +}
>> +
>> +static int realm_rtt_create(struct realm *realm,
>> +			    unsigned long addr,
>> +			    int level,
>> +			    phys_addr_t phys)
>> +{
>> +	addr = ALIGN_DOWN(addr, rme_rtt_level_mapsize(level - 1));
>> +	return rmi_rtt_create(virt_to_phys(realm->rd), phys, addr, level);
>> +}

.......

>> +static void realm_unmap_range_private(struct kvm *kvm,
>> +				      unsigned long start,
>> +				      unsigned long end)
>> +{
>> +	struct realm *realm = &kvm->arch.realm;
>> +	ssize_t map_size = RME_PAGE_SIZE;
>> +	unsigned long next_addr, addr;
>> +
>> +	for (addr = start; addr < end; addr = next_addr) {
>> +		int ret;
>> +
>> +		next_addr = ALIGN(addr + 1, map_size);
>> +

Is that next_addr update needed? 


>> +		ret = realm_destroy_protected(realm, addr, &next_addr);
>> +
>> +		if (WARN_ON(ret))
>> +			break;
>