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From: Oliver Upton To: Raghavendra Rao Ananta Cc: Marc Zyngier , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH] KVM: arm64: Set/unset vGIC v4 forwarding if direct IRQs are supported Message-ID: References: <20250728223710.129440-1-rananta@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250728223710.129440-1-rananta@google.com> X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250729_073727_245553_B330B6A0 X-CRM114-Status: GOOD ( 16.39 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Raghu, Thanks for reporting this so quickly :) On Mon, Jul 28, 2025 at 10:37:10PM +0000, Raghavendra Rao Ananta wrote: > diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c > index e7e284d47a77..873a190bcff7 100644 > --- a/arch/arm64/kvm/vgic/vgic-v4.c > +++ b/arch/arm64/kvm/vgic/vgic-v4.c > @@ -433,7 +433,7 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int virq, > unsigned long flags; > int ret = 0; > > - if (!vgic_supports_direct_msis(kvm)) > + if (!vgic_supports_direct_irqs(kvm)) > return 0; > > /* > @@ -533,7 +533,7 @@ int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int host_irq) > unsigned long flags; > int ret = 0; > > - if (!vgic_supports_direct_msis(kvm)) > + if (!vgic_supports_direct_irqs(kvm)) > return 0; I'm not sure this is what we want, since a precondition of actually doing vLPI injection is the guest having an ITS. Could you try the following? Thanks, Oliver diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c index a3ef185209e9..70d50c77e5dc 100644 --- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c +++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c @@ -50,6 +50,14 @@ bool vgic_has_its(struct kvm *kvm) bool vgic_supports_direct_msis(struct kvm *kvm) { + /* + * Deliberately conflate vLPI and vSGI support on GICv4.1 hardware, + * indirectly allowing userspace to control whether or not vPEs are + * allocated for the VM. + */ + if (system_supports_direct_sgis() && !vgic_supports_direct_sgis(kvm)) + return false; + return kvm_vgic_global_state.has_gicv4 && vgic_has_its(kvm); } diff --git a/arch/arm64/kvm/vgic/vgic.h b/arch/arm64/kvm/vgic/vgic.h index 1384a04c0784..de1c1d3261c3 100644 --- a/arch/arm64/kvm/vgic/vgic.h +++ b/arch/arm64/kvm/vgic/vgic.h @@ -396,15 +396,7 @@ bool vgic_supports_direct_sgis(struct kvm *kvm); static inline bool vgic_supports_direct_irqs(struct kvm *kvm) { - /* - * Deliberately conflate vLPI and vSGI support on GICv4.1 hardware, - * indirectly allowing userspace to control whether or not vPEs are - * allocated for the VM. - */ - if (system_supports_direct_sgis()) - return vgic_supports_direct_sgis(kvm); - - return vgic_supports_direct_msis(kvm); + return vgic_supports_direct_msis(kvm) || vgic_supports_direct_sgis(kvm); } int vgic_v4_init(struct kvm *kvm);