[PATCH 6/8] KVM: arm-vgic: Add vgic reg access from dev attr
Christoffer Dall
christoffer.dall at linaro.org
Wed Sep 25 16:38:03 EDT 2013
On Sun, Aug 25, 2013 at 04:21:58PM +0100, Alexander Graf wrote:
>
> On 23.08.2013, at 20:20, 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 at linaro.org>
> > ---
> > Documentation/virtual/kvm/devices/arm-vgic.txt | 35 ++++++
> > virt/kvm/arm/vgic.c | 143 ++++++++++++++++++++++++
> > 2 files changed, 178 insertions(+)
> >
> > diff --git a/Documentation/virtual/kvm/devices/arm-vgic.txt b/Documentation/virtual/kvm/devices/arm-vgic.txt
> > index c9febb2..1b68475 100644
> > --- a/Documentation/virtual/kvm/devices/arm-vgic.txt
> > +++ b/Documentation/virtual/kvm/devices/arm-vgic.txt
> > @@ -19,3 +19,38 @@ 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
> > +
> > + 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)
> > +
> > + The offsetspecifies the offset from the "CPU interface base address" as
>
> offset specifies
>
> > + 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.
> > + 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 629caeb..e31625c 100644
> > --- a/virt/kvm/arm/vgic.c
> > +++ b/virt/kvm/arm/vgic.c
> > @@ -591,11 +591,29 @@ 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.
> > */
> > struct mmio_range {
> > phys_addr_t base;
> > @@ -665,6 +683,16 @@ 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,
> > + },
> > {}
> > };
> >
> > @@ -1543,6 +1571,80 @@ 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 };
> > +
> > +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)
> > + memcpy(mmio.data, reg, sizeof(*reg));
>
> Is this endianness safe?
>
With a big-endian kernel, no. But I suspect that breaks KVM elsewhere
too. However, this is actually nicer:
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index ea7fb5c..191ff9f 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1622,7 +1622,7 @@ static int vgic_attr_regs_access(struct kvm_device *dev,
mmio.len = 4;
mmio.is_write = is_write;
if (is_write)
- memcpy(mmio.data, reg, sizeof(*reg));
+ 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);
@@ -1638,7 +1638,7 @@ static int vgic_attr_regs_access(struct kvm_device *dev,
spin_unlock(&vcpu->kvm->arch.vgic.lock);
if (!is_write)
- memcpy(reg, mmio.data, sizeof(*reg));
+ *reg = mmio_data_read(mmio, ~0);
return 0;
}
Thanks,
-Christoffer
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