Patchwork [v6,02/13] KVM: ARM: Introduce KVM_SET_DEVICE_ADDRESS ioctl

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Submitter Christoffer Dall
Date Jan. 16, 2013, 6 p.m.
Message ID <20130116180028.29393.62418.stgit@ubuntu>
Download mbox | patch
Permalink /patch/212916/
State New
Headers show

Comments

Christoffer Dall - Jan. 16, 2013, 6 p.m.
On ARM (and possibly other architectures) some bits are specific to the
model being emulated for the guest and user space needs a way to tell
the kernel about those bits.  An example is mmio device base addresses,
where KVM must know the base address for a given device to properly
emulate mmio accesses within a certain address range or directly map a
device with virtualiation extensions into the guest address space.

We try to make this API slightly more generic than for our specific use,
but so far only the VGIC uses this feature.

Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
---
 Documentation/virtual/kvm/api.txt |   37 +++++++++++++++++++++++++++++++++++++
 arch/arm/include/uapi/asm/kvm.h   |   13 +++++++++++++
 arch/arm/kvm/arm.c                |   23 ++++++++++++++++++++++-
 include/uapi/linux/kvm.h          |    8 ++++++++
 4 files changed, 80 insertions(+), 1 deletion(-)
Peter Maydell - Jan. 17, 2013, 5:37 p.m.
On 16 January 2013 18:00, Christoffer Dall
<c.dall@virtualopensystems.com> wrote:
> KVM: ARM: Introduce KVM_SET_DEVICE_ADDRESS ioctl

Patch subject needs updating with new name of this ioctl
(KVM_ARM_SET_DEVICE_ADDR)...

> On ARM (and possibly other architectures) some bits are specific to the
> model being emulated for the guest and user space needs a way to tell
> the kernel about those bits.  An example is mmio device base addresses,
> where KVM must know the base address for a given device to properly
> emulate mmio accesses within a certain address range or directly map a
> device with virtualiation extensions into the guest address space.

"virtualization", while I'm here.

> --- a/arch/arm/include/uapi/asm/kvm.h
> +++ b/arch/arm/include/uapi/asm/kvm.h
> @@ -65,6 +65,19 @@ struct kvm_regs {
>  #define KVM_ARM_TARGET_CORTEX_A15      0
>  #define KVM_ARM_NUM_TARGETS            1
>
> +/* KVM_SET_DEVICE_ADDRESS ioctl id encoding */
> +#define KVM_DEVICE_TYPE_SHIFT          0
> +#define KVM_DEVICE_TYPE_MASK           (0xffff << KVM_DEVICE_TYPE_SHIFT)
> +#define KVM_DEVICE_ID_SHIFT            16
> +#define KVM_DEVICE_ID_MASK             (0xffff << KVM_DEVICE_ID_SHIFT)

...and this comment and I guess these constant names presumably
should have "ARM" in them?

> +/* Available with KVM_CAP_SET_DEVICE_ADDR */

KVM_CAP_ARM_SET_DEVICE_ADDR.

-- PMM

Patch

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index c25439a..4505f86 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2210,6 +2210,43 @@  This ioctl returns the guest registers that are supported for the
 KVM_GET_ONE_REG/KVM_SET_ONE_REG calls.
 
 
+4.80 KVM_ARM_SET_DEVICE_ADDR
+
+Capability: KVM_CAP_ARM_SET_DEVICE_ADDR
+Architectures: arm
+Type: vm ioctl
+Parameters: struct kvm_arm_device_address (in)
+Returns: 0 on success, -1 on error
+Errors:
+  ENODEV: The device id is unknown
+  ENXIO:  Device not supported on current system
+  EEXIST: Address already set
+  E2BIG:  Address outside guest physical address space
+
+struct kvm_arm_device_addr {
+	__u64 id;
+	__u64 addr;
+};
+
+Specify a device address in the guest's physical address space where guests
+can access emulated or directly exposed devices, which the host kernel needs
+to know about. The id field is an architecture specific identifier for a
+specific device.
+
+ARM divides the id field into two parts, a device id and an address type id
+specific to the individual device.
+
+  bits:  | 63        ...       32 | 31    ...    16 | 15    ...    0 |
+  field: |        0x00000000      |     device id   |  addr type id  |
+
+ARM currently only require this when using the in-kernel GIC support for the
+hardware VGIC features, using KVM_ARM_DEVICE_VGIC_V2 as the device id.  When
+setting the base address for the guest's mapping of the VGIC virtual CPU
+and distributor interface, the ioctl must be called after calling
+KVM_CREATE_IRQCHIP, but before calling KVM_RUN on any of the VCPUs.  Calling
+this ioctl twice for any of the base addresses will return -EEXIST.
+
+
 5. The kvm_run structure
 ------------------------
 
diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h
index 3303ff5..d6c8b9c 100644
--- a/arch/arm/include/uapi/asm/kvm.h
+++ b/arch/arm/include/uapi/asm/kvm.h
@@ -65,6 +65,19 @@  struct kvm_regs {
 #define KVM_ARM_TARGET_CORTEX_A15	0
 #define KVM_ARM_NUM_TARGETS		1
 
+/* KVM_SET_DEVICE_ADDRESS ioctl id encoding */
+#define KVM_DEVICE_TYPE_SHIFT		0
+#define KVM_DEVICE_TYPE_MASK		(0xffff << KVM_DEVICE_TYPE_SHIFT)
+#define KVM_DEVICE_ID_SHIFT		16
+#define KVM_DEVICE_ID_MASK		(0xffff << KVM_DEVICE_ID_SHIFT)
+
+/* Supported device IDs */
+#define KVM_ARM_DEVICE_VGIC_V2		0
+
+/* Supported VGIC address types  */
+#define KVM_VGIC_V2_ADDR_TYPE_DIST	0
+#define KVM_VGIC_V2_ADDR_TYPE_CPU	1
+
 #define KVM_ARM_VCPU_POWER_OFF		0 /* CPU is started in OFF state */
 
 struct kvm_vcpu_init {
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 6ff5337..6ab0040 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -167,6 +167,8 @@  int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_COALESCED_MMIO:
 		r = KVM_COALESCED_MMIO_PAGE_OFFSET;
 		break;
+	case KVM_CAP_ARM_SET_DEVICE_ADDR:
+		r = 1;
 	case KVM_CAP_NR_VCPUS:
 		r = num_online_cpus();
 		break;
@@ -822,10 +824,29 @@  int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
 	return -EINVAL;
 }
 
+static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm,
+					struct kvm_arm_device_addr *dev_addr)
+{
+	return -ENODEV;
+}
+
 long kvm_arch_vm_ioctl(struct file *filp,
 		       unsigned int ioctl, unsigned long arg)
 {
-	return -EINVAL;
+	struct kvm *kvm = filp->private_data;
+	void __user *argp = (void __user *)arg;
+
+	switch (ioctl) {
+	case KVM_ARM_SET_DEVICE_ADDR: {
+		struct kvm_arm_device_addr dev_addr;
+
+		if (copy_from_user(&dev_addr, argp, sizeof(dev_addr)))
+			return -EFAULT;
+		return kvm_vm_ioctl_set_device_addr(kvm, &dev_addr);
+	}
+	default:
+		return -EINVAL;
+	}
 }
 
 static void cpu_init_hyp_mode(void *vector)
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 500acda..9ff7f70 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -636,6 +636,7 @@  struct kvm_ppc_smmu_info {
 #define KVM_CAP_IRQFD_RESAMPLE 82
 #define KVM_CAP_PPC_BOOKE_WATCHDOG 83
 #define KVM_CAP_PPC_HTAB_FD 84
+#define KVM_CAP_ARM_SET_DEVICE_ADDR 85
 #define KVM_CAP_ARM_PSCI 86
 
 #ifdef KVM_CAP_IRQ_ROUTING
@@ -784,6 +785,11 @@  struct kvm_msi {
 	__u8  pad[16];
 };
 
+struct kvm_arm_device_addr {
+	__u64 id;
+	__u64 addr;
+};
+
 /*
  * ioctls for VM fds
  */
@@ -869,6 +875,8 @@  struct kvm_s390_ucas_mapping {
 #define KVM_ALLOCATE_RMA	  _IOR(KVMIO,  0xa9, struct kvm_allocate_rma)
 /* Available with KVM_CAP_PPC_HTAB_FD */
 #define KVM_PPC_GET_HTAB_FD	  _IOW(KVMIO,  0xaa, struct kvm_get_htab_fd)
+/* Available with KVM_CAP_SET_DEVICE_ADDR */
+#define KVM_ARM_SET_DEVICE_ADDR	  _IOW(KVMIO,  0xab, struct kvm_arm_device_addr)
 
 /*
  * ioctls for vcpu fds