On 2013-10-22 10:08, Christoffer Dall wrote:
Add infrastructure to handle distributor and cpu interface register
accesses through the KVM_{GET/SET}_DEVICE_ATTR interface by adding
the
KVM_DEV_ARM_VGIC_GRP_DIST_REGS and KVM_DEV_ARM_VGIC_GRP_CPU_REGS
groups
and defining the semantics of the attr field to be the MMIO offset as
specified in the GICv2 specs.
Missing register accesses or other changes in individual register
access
functions to support save/restore of the VGIC state is added in
subsequent patches.
Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Reviewed-by: Alexander Graf <agraf@xxxxxxx>
---
Changelog[v2]:
- Added implementation specific format for the GICC_APRn registers.
---
Documentation/virtual/kvm/devices/arm-vgic.txt | 50 +++++++++
virt/kvm/arm/vgic.c | 143
++++++++++++++++++++++++
2 files changed, 193 insertions(+)
diff --git a/Documentation/virtual/kvm/devices/arm-vgic.txt
b/Documentation/virtual/kvm/devices/arm-vgic.txt
index c9febb2..e6416f8e 100644
--- a/Documentation/virtual/kvm/devices/arm-vgic.txt
+++ b/Documentation/virtual/kvm/devices/arm-vgic.txt
@@ -19,3 +19,53 @@ Groups:
KVM_VGIC_V2_ADDR_TYPE_CPU (rw, 64-bit)
Base address in the guest physical address space of the GIC
virtual cpu
interface register mappings.
+
+ KVM_DEV_ARM_VGIC_GRP_DIST_REGS
+ Attributes:
+ The attr field of kvm_device_attr encodes two values:
+ bits: | 63 .... 40 | 39 .. 32 | 31 .... 0 |
+ values: | reserved | cpu id | offset |
+
+ All distributor regs are (rw, 32-bit)
+
+ The offset is relative to the "Distributor base address" as
defined in the
+ GICv2 specs. Getting or setting such a register has the same
effect as
+ reading or writing the register on the actual hardware from the
cpu
+ specified with cpu id field. Note that most distributor fields
are not
+ banked, but return the same value regardless of the cpu id used
to access
+ the register.
+ Limitations:
+ - Priorities are not implemented, and registers are RAZ/WI
+ Errors:
+ - ENODEV: Getting or setting this register is not yet supported
-ENODEV?
+ KVM_DEV_ARM_VGIC_GRP_CPU_REGS
+ Attributes:
+ The attr field of kvm_device_attr encodes two values:
+ bits: | 63 .... 40 | 39 .. 32 | 31 .... 0 |
+ values: | reserved | cpu id | offset |
+
+ All CPU regs are (rw, 32-bit)
Nit: CPU interface registers
+ The offset specifies the offset from the "CPU interface base
address" as
+ defined in the GICv2 specs. Getting or setting such a register
has the
+ same effect as reading or writing the register on the actual
hardware.
+
+ The Active Priorities Registers APRn are implementation defined,
so we set a
+ fixed format for our implementation that fits with the model of
a "GICv2
+ impementation without the security extensions" which we present
to the
implementation
+ guest. This interface always exposes four register APR[0-3]
describing the
+ maximum possible 128 preemption levels. The semantics of the
register
+ indicate if any interrupts in a given preemption level are in
the active
+ state by setting the corresponding bit.
+
+ Thus, preemption level X has one or more active interrupts if
and only if:
+
+ APRn[X mod 32] == 0b1, where n = X / 32
+
+ Bits for undefined preemption levels are RAZ/WI.
+
+ Limitations:
+ - Priorities are not implemented, and registers are RAZ/WI
+ Errors:
+ - ENODEV: Getting or setting this register is not yet supported
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 1148a2e..f2dc72a 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -589,11 +589,29 @@ static bool handle_mmio_sgi_reg(struct kvm_vcpu
*vcpu,
return false;
}
+static bool handle_mmio_sgi_clear(struct kvm_vcpu *vcpu,
+ struct kvm_exit_mmio *mmio,
+ phys_addr_t offset)
+{
+ return false;
+}
+
+static bool handle_mmio_sgi_set(struct kvm_vcpu *vcpu,
+ struct kvm_exit_mmio *mmio,
+ phys_addr_t offset)
+{
+ return false;
+}
+
/*
* I would have liked to use the kvm_bus_io_*() API instead, but it
* cannot cope with banked registers (only the VM pointer is passed
* around, and we need the vcpu). One of these days, someone please
* fix it!
+ *
+ * Note that the handle_mmio implementations should not use the
phys_addr
+ * field from the kvm_exit_mmio struct as this will not have any
sane values
+ * when used to save/restore state from user space.
This is quite ugly... I don't think we'd ever use that field directly,
but reusing a well known structure for that purpose is very messy. I
believe we'd be better off creating our own structure instead of
re-purposing am existing one.
The other possibility would be to properly fill-in the phys_addr field.
How difficult would that be?
*/
struct mmio_range {
phys_addr_t base;
@@ -663,6 +681,16 @@ static const struct mmio_range
vgic_dist_ranges[] = {
.len = 4,
.handle_mmio = handle_mmio_sgi_reg,
},
+ {
+ .base = GIC_DIST_SGI_CLEAR,
+ .len = VGIC_NR_SGIS,
+ .handle_mmio = handle_mmio_sgi_clear,
+ },
+ {
+ .base = GIC_DIST_SGI_SET,
+ .len = VGIC_NR_SGIS,
+ .handle_mmio = handle_mmio_sgi_set,
+ },
{}
};
@@ -1541,6 +1569,80 @@ int kvm_vgic_addr(struct kvm *kvm, unsigned
long type, u64 *addr, bool write)
return r;
}
+static bool handle_cpu_mmio_misc(struct kvm_vcpu *vcpu,
+ struct kvm_exit_mmio *mmio, phys_addr_t offset)
+{
+ return true;
+}
+
+static const struct mmio_range vgic_cpu_ranges[] = {
+ {
+ .base = GIC_CPU_CTRL,
+ .len = 12,
+ .handle_mmio = handle_cpu_mmio_misc,
+ },
+ {
+ .base = GIC_CPU_ALIAS_BINPOINT,
+ .len = 4,
+ .handle_mmio = handle_cpu_mmio_misc,
+ },
+ {
+ .base = GIC_CPU_ACTIVEPRIO,
+ .len = 16,
+ .handle_mmio = handle_cpu_mmio_misc,
+ },
+ {
+ .base = GIC_CPU_IDENT,
+ .len = 4,
+ .handle_mmio = handle_cpu_mmio_misc,
+ },
+};
+
+static struct kvm_exit_mmio dev_attr_mmio = { .len = 4 };
I'm not very fond of a half-initialized structure here. How about
moving this "4" to the location where it is used?
Actually, what if we have several users of this through
vgic_has_attr_regs at the same time? It feels incredibly racy. I suggest
you nuke it and move it to live on the stack in vgic_has_attr_regs.
+static int vgic_attr_regs_access(struct kvm_device *dev,
+ struct kvm_device_attr *attr,
+ u32 *reg, bool is_write)
+{
+ const struct mmio_range *r = NULL;
+ phys_addr_t offset;
+ int cpuid;
+ struct kvm_vcpu *vcpu;
+ struct kvm_exit_mmio mmio;
+
+ offset = attr->attr & KVM_DEV_ARM_VGIC_OFFSET_MASK;
+ cpuid = (attr->attr & KVM_DEV_ARM_VGIC_CPUID_MASK) >>
+ KVM_DEV_ARM_VGIC_CPUID_SHIFT;
+
+ if (cpuid >= atomic_read(&dev->kvm->online_vcpus))
+ return -EINVAL;
+
+ vcpu = kvm_get_vcpu(dev->kvm, cpuid);
+
+ mmio.len = 4;
+ mmio.is_write = is_write;
+ if (is_write)
+ mmio_data_write(&mmio, ~0, *reg);
+
+ if (attr->group == KVM_DEV_ARM_VGIC_GRP_DIST_REGS)
+ r = find_matching_range(vgic_dist_ranges, &mmio, offset);
+ else if (attr->group == KVM_DEV_ARM_VGIC_GRP_CPU_REGS)
+ r = find_matching_range(vgic_cpu_ranges, &mmio, offset);
How about having a switch statement instead?
+ if (unlikely(!r || !r->handle_mmio))
+ return -ENXIO;
+
+ spin_lock(&vcpu->kvm->arch.vgic.lock);
+ offset -= r->base;
+ r->handle_mmio(vcpu, &mmio, offset);
+ spin_unlock(&vcpu->kvm->arch.vgic.lock);
+
+ if (!is_write)
+ *reg = mmio_data_read(&mmio, ~0);
+
+ return 0;
+}
+
static int vgic_set_attr(struct kvm_device *dev, struct
kvm_device_attr *attr)
{
int r;
@@ -1557,6 +1659,18 @@ static int vgic_set_attr(struct kvm_device
*dev, struct kvm_device_attr *attr)
r = kvm_vgic_addr(dev->kvm, type, &addr, true);
return (r == -ENODEV) ? -ENXIO : r;
}
+
+ case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
+ case KVM_DEV_ARM_VGIC_GRP_CPU_REGS: {
+ u32 __user *uaddr = (u32 __user *)(long)attr->addr;
+ u32 reg;
+
+ if (get_user(reg, uaddr))
+ return -EFAULT;
+
+ return vgic_attr_regs_access(dev, attr, ®, true);
+ }
+
}
return -ENXIO;
@@ -1579,12 +1693,35 @@ static int vgic_get_attr(struct kvm_device
*dev, struct kvm_device_attr *attr)
r = 0;
if (copy_to_user(uaddr, &addr, sizeof(addr)))
return -EFAULT;
+ break;
}
+
+ case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
+ case KVM_DEV_ARM_VGIC_GRP_CPU_REGS: {
+ u32 __user *uaddr = (u32 __user *)(long)attr->addr;
+ u32 reg = 0;
+
+ r = vgic_attr_regs_access(dev, attr, ®, false);
+ if (r)
+ return r;
+ r = put_user(reg, uaddr);
+ break;
+ }
+
}
return r;
}
+static int vgic_has_attr_regs(const struct mmio_range *ranges,
+ phys_addr_t offset)
+{
+ if (find_matching_range(ranges, &dev_attr_mmio, offset))
+ return 0;
+ else
+ return -ENXIO;
+}
+
static int vgic_has_attr(struct kvm_device *dev, struct
kvm_device_attr *attr)
{
phys_addr_t offset;
@@ -1597,6 +1734,12 @@ static int vgic_has_attr(struct kvm_device
*dev, struct kvm_device_attr *attr)
return 0;
}
break;
+ case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
+ offset = attr->attr & KVM_DEV_ARM_VGIC_OFFSET_MASK;
+ return vgic_has_attr_regs(vgic_dist_ranges, offset);
+ case KVM_DEV_ARM_VGIC_GRP_CPU_REGS:
+ offset = attr->attr & KVM_DEV_ARM_VGIC_OFFSET_MASK;
+ return vgic_has_attr_regs(vgic_cpu_ranges, offset);
}
return -ENXIO;
}
--
Who you jivin' with that Cosmik Debris?
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