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Date: Mon, 19 May 2025 19:11:12 +0100
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Subject: Re: [PATCH v8 18/43] KVM: arm64: Handle realm MMIO emulation
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To: Steven Price <steven.price@arm.com>, 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>, 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>, "Aneesh Kumar K . V"
 <aneesh.kumar@kernel.org>
References: <20250416134208.383984-1-steven.price@arm.com>
 <20250416134208.383984-19-steven.price@arm.com>
From: Suzuki K Poulose <suzuki.poulose@arm.com>
In-Reply-To: <20250416134208.383984-19-steven.price@arm.com>
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On 16/04/2025 14:41, Steven Price wrote:
> MMIO emulation for a realm cannot be done directly with the VM's
> registers as they are protected from the host. However, for emulatable
> data aborts, the RMM uses GPRS[0] to provide the read/written value.
> We can transfer this from/to the equivalent VCPU's register entry and
> then depend on the generic MMIO handling code in KVM.
> 
> For a MMIO read, the value is placed in the shared RecExit structure
> during kvm_handle_mmio_return() rather than in the VCPU's register
> entry.
> 
> Signed-off-by: Steven Price <steven.price@arm.com>
> Reviewed-by: Gavin Shan <gshan@redhat.com>

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>