[PATCH v8 5/5] KVM: arm/arm64: add irqfd support

Eric Auger
2015-01-19T16:45:53Z

This patch enables irqfd on arm/arm64.

Both irqfd and resamplefd are supported. Injection is implemented
in vgic.c without routing.

This patch enables CONFIG_HAVE_KVM_EVENTFD and CONFIG_HAVE_KVM_IRQFD.

KVM_CAP_IRQFD is now advertised. KVM_CAP_IRQFD_RESAMPLE capability
automatically is advertised as soon as CONFIG_HAVE_KVM_IRQFD is set.

Irqfd injection is restricted to SPI. The rationale behind not
supporting PPI irqfd injection is that any device using a PPI would
be a private-to-the-CPU device (timer for instance), so its state
would have to be context-switched along with the VCPU and would
require in-kernel wiring anyhow. It is not a relevant use case for
irqfds.

Signed-off-by: Eric Auger <eric.auger@linaro.org>

---
v7 -> v8:
- remove kvm_irq_has_notifier call
- part of dist locking changes now are part of previous patch file
- remove gic_initialized() check in kvm_set_irq
- remove Christoffer's Reviewed-by after this change

v5 -> v6:
- KVM_CAP_IRQFD support depends on vgic_present
- add Christoffer's Reviewed-by

v4 -> v5:
- squash [PATCH v4 3/3] KVM: arm64: add irqfd support into this patch
- some rewording in Documentation/virtual/kvm/api.txt and in vgic
vgic_process_maintenance unlock comment.
- move explanation of why not supporting PPI into commit message
- in case of injection before gic readiness, -ENODEV is returned. It is
up to the user space to avoid this situation.

v3 -> v4:
- reword commit message
- explain why we unlock the distributor before calling kvm_notify_acked_irq
- rename is_assigned_irq into has_notifier
- change EOI and injection kvm_debug format string
- remove error local variable in kvm_set_irq
- Move HAVE_KVM_IRQCHIP unset in a separate patch
- handle case were the irqfd injection is attempted before the vgic is ready.
in such a case the notifier, if any, is called immediatly
- use nr_irqs to test spi is within correct range

v2 -> v3:
- removal of irq.h from eventfd.c put in a separate patch to increase
visibility
- properly expose KVM_CAP_IRQFD capability in arm.c
- remove CONFIG_HAVE_KVM_IRQCHIP meaningfull only if irq_comm.c is used

v1 -> v2:
- rebase on 3.17rc1
- move of the dist unlock in process_maintenance
- remove of dist lock in __kvm_vgic_sync_hwstate
- rewording of the commit message (add resamplefd reference)
- remove irq.h
---
Documentation/virtual/kvm/api.txt | 6 +++++-
arch/arm/include/uapi/asm/kvm.h | 3 +++
arch/arm/kvm/Kconfig | 2 ++
arch/arm/kvm/Makefile | 2 +-
arch/arm/kvm/arm.c | 5 +++++
arch/arm64/include/uapi/asm/kvm.h | 3 +++
arch/arm64/kvm/Kconfig | 2 ++
arch/arm64/kvm/Makefile | 2 +-
virt/kvm/arm/vgic.c | 45 +++++++++++++++++++++++++++++++++++++++
9 files changed, 67 insertions(+), 3 deletions(-)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 0007fef..5ed8088 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2231,7 +2231,7 @@ into the hash PTE second double word).
4.75 KVM_IRQFD

Capability: KVM_CAP_IRQFD
-Architectures: x86 s390
+Architectures: x86 s390 arm arm64
Type: vm ioctl
Parameters: struct kvm_irqfd (in)
Returns: 0 on success, -1 on error
@@ -2257,6 +2257,10 @@ Note that closing the resamplefd is not sufficient to disable the
irqfd. The KVM_IRQFD_FLAG_RESAMPLE is only necessary on assignment
and need not be specified with KVM_IRQFD_FLAG_DEASSIGN.

+On ARM/ARM64, the gsi field in the kvm_irqfd struct specifies the Shared
+Peripheral Interrupt (SPI) index, such that the GIC interrupt ID is
+given by gsi + 32.
+
4.76 KVM_PPC_ALLOCATE_HTAB

Capability: KVM_CAP_PPC_ALLOC_HTAB
diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h
index 0db25bc..2499867 100644
--- a/arch/arm/include/uapi/asm/kvm.h
+++ b/arch/arm/include/uapi/asm/kvm.h
@@ -198,6 +198,9 @@ struct kvm_arch_memory_slot {
/* Highest supported SPI, from VGIC_NR_IRQS */
#define KVM_ARM_IRQ_GIC_MAX 127

+/* One single KVM irqchip, ie. the VGIC */
+#define KVM_NR_IRQCHIPS 1
+
/* PSCI interface */
#define KVM_PSCI_FN_BASE 0x95c1ba5e
#define KVM_PSCI_FN(n) (KVM_PSCI_FN_BASE + (n))
diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
index 9f581b1..e519a40 100644
--- a/arch/arm/kvm/Kconfig
+++ b/arch/arm/kvm/Kconfig
@@ -24,6 +24,7 @@ config KVM
select KVM_MMIO
select KVM_ARM_HOST
depends on ARM_VIRT_EXT && ARM_LPAE
+ select HAVE_KVM_EVENTFD
---help---
Support hosting virtualized guest machines. You will also
need to select one or more of the processor modules below.
@@ -55,6 +56,7 @@ config KVM_ARM_MAX_VCPUS
config KVM_ARM_VGIC
bool "KVM support for Virtual GIC"
depends on KVM_ARM_HOST && OF
+ select HAVE_KVM_IRQFD
default y
---help---
Adds support for a hardware assisted, in-kernel GIC emulation.
diff --git a/arch/arm/kvm/Makefile b/arch/arm/kvm/Makefile
index f7057ed..859db09 100644
--- a/arch/arm/kvm/Makefile
+++ b/arch/arm/kvm/Makefile
@@ -15,7 +15,7 @@ AFLAGS_init.o := -Wa,-march=armv7-a$(plus_virt)
AFLAGS_interrupts.o := -Wa,-march=armv7-a$(plus_virt)

KVM := ../../../virt/kvm
-kvm-arm-y = $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o
+kvm-arm-y = $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o

obj-y += kvm-arm.o init.o interrupts.o
obj-y += arm.o handle_exit.o guest.o mmu.o emulate.o reset.o
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 9c905b4..8f8c1da 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -172,6 +172,11 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_IRQCHIP:
r = vgic_present;
break;
+#ifdef CONFIG_HAVE_KVM_IRQFD
+ case KVM_CAP_IRQFD:
+ r = vgic_present;
+ break;
+#endif
case KVM_CAP_DEVICE_CTRL:
case KVM_CAP_USER_MEMORY:
case KVM_CAP_SYNC_MMU:
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 480af34..b35c95a 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -184,6 +184,9 @@ struct kvm_arch_memory_slot {
/* Highest supported SPI, from VGIC_NR_IRQS */
#define KVM_ARM_IRQ_GIC_MAX 127

+/* One single KVM irqchip, ie. the VGIC */
+#define KVM_NR_IRQCHIPS 1
+
/* PSCI interface */
#define KVM_PSCI_FN_BASE 0x95c1ba5e
#define KVM_PSCI_FN(n) (KVM_PSCI_FN_BASE + (n))
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 279e1a0..09c25c2 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -26,6 +26,7 @@ config KVM
select KVM_ARM_HOST
select KVM_ARM_VGIC
select KVM_ARM_TIMER
+ select HAVE_KVM_EVENTFD
---help---
Support hosting virtualized guest machines.

@@ -50,6 +51,7 @@ config KVM_ARM_MAX_VCPUS
config KVM_ARM_VGIC
bool
depends on KVM_ARM_HOST && OF
+ select HAVE_KVM_IRQFD
---help---
Adds support for a hardware assisted, in-kernel GIC emulation.

diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 32a0961..2e6b827 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -11,7 +11,7 @@ ARM=../../../arch/arm/kvm

obj-$(CONFIG_KVM_ARM_HOST) += kvm.o

-kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o
+kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o
kvm-$(CONFIG_KVM_ARM_HOST) += $(ARM)/arm.o $(ARM)/mmu.o $(ARM)/mmio.o
kvm-$(CONFIG_KVM_ARM_HOST) += $(ARM)/psci.o $(ARM)/perf.o

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 18060ea..2c269dd 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1449,6 +1449,7 @@ static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
u32 status = vgic_get_interrupt_status(vcpu);
struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
bool level_pending = false;
+ struct kvm *kvm = vcpu->kvm;

kvm_debug("STATUS = %08x\n", status);

@@ -1484,6 +1485,17 @@ static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
*/
vgic_dist_irq_clear_soft_pend(vcpu, vlr.irq);

+ /*
+ * kvm_notify_acked_irq calls kvm_set_irq()
+ * to reset the IRQ level. Need to release the
+ * lock for kvm_set_irq to grab it.
+ */
+ spin_unlock(&dist->lock);
+
+ kvm_notify_acked_irq(kvm, 0,
+ vlr.irq - VGIC_NR_PRIVATE_IRQS);
+ spin_lock(&dist->lock);
+
/* Any additional pending interrupt? */
if (vgic_dist_irq_get_level(vcpu, vlr.irq)) {
vgic_cpu_irq_set(vcpu, vlr.irq);
@@ -2490,3 +2502,36 @@ out_free_irq:
free_percpu_irq(vgic->maint_irq, kvm_get_running_vcpus());
return ret;
}
+
+int kvm_irq_map_gsi(struct kvm *kvm,
+ struct kvm_kernel_irq_routing_entry *entries,
+ int gsi)
+{
+ return gsi;
+}
+
+int kvm_irq_map_chip_pin(struct kvm *kvm, unsigned irqchip, unsigned pin)
+{
+ return pin;
+}
+
+int kvm_set_irq(struct kvm *kvm, int irq_source_id,
+ u32 irq, int level, bool line_status)
+{
+ unsigned int spi = irq + VGIC_NR_PRIVATE_IRQS;
+
+ kvm_debug("irqfd sets vIRQ %d to %d\n", irq, level);
+
+ if (spi > kvm->arch.vgic.nr_irqs)
+ return -EINVAL;
+ return kvm_vgic_inject_irq(kvm, 0, spi, level);
+
+}
+
+/* MSI not implemented yet */
+int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
+ struct kvm *kvm, int irq_source_id,
+ int level, bool line_status)
+{
+ return 0;
+}
--
1.9.1