linux-kernel - Re: [PATCH v4 21/43] arm64: RME: Runtime faulting of memory

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <8c0f787c-35d4-4cb1-84d3-ff3f2e3f003a@arm.com>
Date: Thu, 22 Aug 2024 16:14:18 +0100
From: Steven Price <steven.price@....com>
To: "Aneesh Kumar K.V" <aneesh.kumar@...nel.org>, 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>,
 Suzuki K Poulose <suzuki.poulose@....com>, 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 v4 21/43] arm64: RME: Runtime faulting of memory

On 22/08/2024 04:32, Aneesh Kumar K.V wrote:
> Steven Price <steven.price@....com> writes:
> 
>> At runtime if the realm guest accesses memory which hasn't yet been
>> mapped then KVM needs to either populate the region or fault the guest.
>>
>> For memory in the lower (protected) region of IPA a fresh page is
>> provided to the RMM which will zero the contents. For memory in the
>> upper (shared) region of IPA, the memory from the memslot is mapped
>> into the realm VM non secure.
>>
>> Signed-off-by: Steven Price <steven.price@....com>
>> ---
>> Changes since v2:
>>  * Avoid leaking memory if failing to map it in the realm.
>>  * Correctly mask RTT based on LPA2 flag (see rtt_get_phys()).
>>  * Adapt to changes in previous patches.
>>
> 
> ....
> 
>> -	gfn = ipa >> PAGE_SHIFT;
>> +	gfn = (ipa & ~gpa_stolen_mask) >> PAGE_SHIFT;
>>  	memslot = gfn_to_memslot(vcpu->kvm, gfn);
>> +
>> +	if (kvm_slot_can_be_private(memslot)) {
>> +		ret = private_memslot_fault(vcpu, fault_ipa, memslot);
>> +		if (ret != -EAGAIN)
>> +			goto out;
>> +	}
>>
> 
> Shouldn't this be s/fault_ipa/ipa ?

Well they should both be the same unless we're in some scary parallel
universe where we have nested virtualisation *and* realms at the same
time (shudder!). But yes "ipa" would be more consistent so I'll change it!

Steve

> 	ret = private_memslot_fault(vcpu, ipa, memslot);
> 
> -aneesh