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[129.215.164.122]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a06d4a8150sm2199951f8f.7.2025.04.24.07.14.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Apr 2025 07:14:28 -0700 (PDT) From: Karim Manaouil To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev Cc: Karim Manaouil , Alexander Graf , Alex Elder , Catalin Marinas , Fuad Tabba , Joey Gouly , Jonathan Corbet , Marc Zyngier , Mark Brown , Mark Rutland , Oliver Upton , Paolo Bonzini , Prakruthi Deepak Heragu , Quentin Perret , Rob Herring , Srinivas Kandagatla , Srivatsa Vaddagiri , Will Deacon , Haripranesh S , Carl van Schaik , Murali Nalajala , Sreenivasulu Chalamcharla , Trilok Soni , Stefan Schmidt Subject: [RFC PATCH 33/34] KVM: gunyah: Implement irqfd interface Date: Thu, 24 Apr 2025 15:13:40 +0100 Message-Id: <20250424141341.841734-34-karim.manaouil@linaro.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250424141341.841734-1-karim.manaouil@linaro.org> References: <20250424141341.841734-1-karim.manaouil@linaro.org> Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Enables support for injecting interrupts into guest vCPUs via KVM's irqfd interface. Irqfds are requested from userspace via KVM_IRQFD ioctl. kvm_arch_irqfd_init() implementation, in Gunyah, then creates a resource ticket for the irqfd. The userspace must also create a devicetree node to create a doorbell with the corresponding label. Later after VM configuration (in gunyah_vm_start()), the resource ticket will be populated and the irqfd instance will be bound to its corresponding doorbell (identified with a capability id). When userspace asserts the irq line, irqfd->set_irq() callback is called to inject an interrupt into the guest via a hypercall. Signed-off-by: Karim Manaouil --- arch/arm64/kvm/gunyah.c | 100 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 100 insertions(+) diff --git a/arch/arm64/kvm/gunyah.c b/arch/arm64/kvm/gunyah.c index df922be2429e..23b9128bf5b1 100644 --- a/arch/arm64/kvm/gunyah.c +++ b/arch/arm64/kvm/gunyah.c @@ -29,6 +29,14 @@ #define WRITE_TAG (1 << 0) #define SHARE_TAG (1 << 1) +struct gunyah_irqfd { + struct gunyah_vm *ghvm; + struct gunyah_resource *ghrsc; + struct gunyah_vm_resource_ticket ticket; + struct kvm_kernel_irqfd irqfd; + bool level; +}; + static int gunyah_vm_start(struct gunyah_vm *ghvm); static enum kvm_mode kvm_mode = KVM_MODE_DEFAULT; @@ -852,6 +860,98 @@ static int gunyah_start_paging(struct gunyah_vm *ghvm) return ret; } +static bool gunyah_irqfd_populate(struct gunyah_vm_resource_ticket *ticket, + struct gunyah_resource *ghrsc) +{ + struct gunyah_irqfd *irqfd = + container_of(ticket, struct gunyah_irqfd, ticket); + int ret; + + if (irqfd->ghrsc) { + pr_warn("irqfd%d already got a Gunyah resource", irqfd->ticket.label); + return false; + } + + irqfd->ghrsc = ghrsc; + if (irqfd->level) { + /* Configure the bell to trigger when bit 0 is asserted (see + * irq_wakeup) and for bell to automatically clear bit 0 once + * received by the VM (ack_mask). need to make sure bit 0 is cleared right away, + * otherwise the line will never be deasserted. Emulating edge + * trigger interrupt does not need to set either mask + * because irq is listed only once per gunyah_hypercall_bell_send + */ + ret = gunyah_hypercall_bell_set_mask(irqfd->ghrsc->capid, 1, 1); + if (ret) + pr_warn("irq %d couldn't be set as level triggered." + "Might cause IRQ storm if asserted\n", + irqfd->ticket.label); + } + + return true; +} + +static void gunyah_irqfd_unpopulate(struct gunyah_vm_resource_ticket *ticket, + struct gunyah_resource *ghrsc) +{ +} + +static int gunyah_set_irq(struct kvm_kernel_irqfd *kvm_irqfd) +{ + int ret; + struct gunyah_irqfd *irqfd = + container_of(kvm_irqfd, struct gunyah_irqfd, irqfd); + + if (irqfd->ghrsc) { + if (gunyah_hypercall_bell_send(irqfd->ghrsc->capid, 1, NULL)) { + pr_err_ratelimited("Failed to inject interrupt %d: %d\n", + irqfd->ticket.label, ret); + return -1; + } + } else { + pr_err_ratelimited("Premature injection of interrupt\n"); + return -1; + } + + return 1; +} + +struct kvm_kernel_irqfd *kvm_arch_irqfd_alloc(void) +{ + struct gunyah_irqfd *irqfd; + + irqfd = kzalloc(sizeof(struct gunyah_irqfd), GFP_KERNEL); + if (!irqfd) + return NULL; + + return &irqfd->irqfd; +} + +void kvm_arch_irqfd_free(struct kvm_kernel_irqfd *kvm_irqfd) +{ + struct gunyah_irqfd *irqfd = container_of(kvm_irqfd, struct gunyah_irqfd, irqfd); + + gunyah_vm_remove_resource_ticket(irqfd->ghvm, &irqfd->ticket); + kfree(irqfd); +} + +int kvm_arch_irqfd_init(struct kvm_kernel_irqfd *kvm_irqfd) +{ + struct gunyah_vm *ghvm = container_of(kvm_irqfd->kvm, struct gunyah_vm, kvm); + struct gunyah_irqfd *irqfd = container_of(kvm_irqfd, struct gunyah_irqfd, irqfd); + + kvm_irqfd->set_irq = gunyah_set_irq; + + irqfd->ghvm = ghvm; + + irqfd->ticket.resource_type = GUNYAH_RESOURCE_TYPE_BELL_TX; + irqfd->ticket.label = kvm_irqfd->gsi; + irqfd->ticket.populate = gunyah_irqfd_populate; + irqfd->ticket.unpopulate = gunyah_irqfd_unpopulate; + + return gunyah_vm_add_resource_ticket(ghvm, &irqfd->ticket); +} + int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) { return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;