linux-kernel - Re: [PATCH v4 1/3] KVM: arm64: VM exit to userspace to handle SEA

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Message-ID: <86jz06vjsj.wl-maz@kernel.org>
Date: Mon, 03 Nov 2025 22:22:04 +0000
From: Marc Zyngier <maz@...nel.org>
To: Jose Marinho <jose.marinho@....com>
Cc: Jiaqi Yan <jiaqiyan@...gle.com>,
	oliver.upton@...ux.dev,
	duenwen@...gle.com,
	rananta@...gle.com,
	jthoughton@...gle.com,
	vsethi@...dia.com,
	jgg@...dia.com,
	joey.gouly@....com,
	suzuki.poulose@....com,
	yuzenghui@...wei.com,
	catalin.marinas@....com,
	will@...nel.org,
	pbonzini@...hat.com,
	corbet@....net,
	shuah@...nel.org,
	kvm@...r.kernel.org,
	kvmarm@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org,
	linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v4 1/3] KVM: arm64: VM exit to userspace to handle SEA

On Mon, 03 Nov 2025 18:17:00 +0000,
Jose Marinho <jose.marinho@....com> wrote:
> 
> > +	/*
> > +	 * Exit to userspace, and provide faulting guest virtual and physical
> > +	 * addresses in case userspace wants to emulate SEA to guest by
> > +	 * writing to FAR_ELx and HPFAR_ELx registers.
> > +	 */
> > +	memset(&run->arm_sea, 0, sizeof(run->arm_sea));
> > +	run->exit_reason = KVM_EXIT_ARM_SEA;
> > +	run->arm_sea.esr = esr & esr_mask;
> > +
> > +	if (!(esr & ESR_ELx_FnV))
> > +		run->arm_sea.gva = kvm_vcpu_get_hfar(vcpu) > +
> > +	ipa = kvm_vcpu_get_fault_ipa(vcpu);
> > +	if (ipa != INVALID_GPA) {
> > +		run->arm_sea.flags |= KVM_EXIT_ARM_SEA_FLAG_GPA_VALID;
> > +		run->arm_sea.gpa = ipa;
> 
> Are we interested in the value of PFAR_EL2 (if FEAT_PFAR implemented)?

We don't have any support for PFAR, and I don't think we have any plan
to support it in the near future. If anything, the rest of the kernel
should start by growing support for it before we start dragging it
into KVM.

	M.

-- 
Without deviation from the norm, progress is not possible.