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Date: Fri, 1 Nov 2024 16:22:46 +0000
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Subject: Re: [PATCH v5 09/43] arm64: RME: ioctls to create and configure
 realms
To: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>, kvm@vger.kernel.org,
 kvmarm@lists.linux.dev
Cc: Catalin Marinas <catalin.marinas@arm.com>, Marc Zyngier <maz@kernel.org>,
 Will Deacon <will@kernel.org>, James Morse <james.morse@arm.com>,
 Oliver Upton <oliver.upton@linux.dev>,
 Suzuki K Poulose <suzuki.poulose@arm.com>, Zenghui Yu
 <yuzenghui@huawei.com>, linux-arm-kernel@lists.infradead.org,
 linux-kernel@vger.kernel.org, Joey Gouly <joey.gouly@arm.com>,
 Alexandru Elisei <alexandru.elisei@arm.com>,
 Christoffer Dall <christoffer.dall@arm.com>, Fuad Tabba <tabba@google.com>,
 linux-coco@lists.linux.dev,
 Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>,
 Gavin Shan <gshan@redhat.com>, Shanker Donthineni <sdonthineni@nvidia.com>,
 Alper Gun <alpergun@google.com>
References: <20241004152804.72508-1-steven.price@arm.com>
 <20241004152804.72508-10-steven.price@arm.com> <yq5acyjic9dm.fsf@kernel.org>
From: Steven Price <steven.price@arm.com>
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In-Reply-To: <yq5acyjic9dm.fsf@kernel.org>
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On 30/10/2024 07:55, Aneesh Kumar K.V wrote:
> Steven Price <steven.price@arm.com> writes:
> 
>> +
>> +out_undelegate_tables:
>> +	while (--i >= 0) {
>> +		phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i * PAGE_SIZE;
>> +
>> +		WARN_ON(rmi_granule_undelegate(pgd_phys));
>> +	}
>> +	WARN_ON(rmi_granule_undelegate(rd_phys));
>> +free_rd:
>> +	free_page((unsigned long)rd);
>> +	return r;
>> +}
>> +
> 
> we should avoid that free_page on an undelegate failure? rd_phys we can
> handle here. Not sure how to handle the pgd_phys.

Good point. I think for pgd_phys setting kvm->arch.mmu.pgt=NULL should
be sufficient to prevent the pages being freed.

Thanks,
Steve