On 02/14/2013 06:01:08 PM, Paul Mackerras wrote:
From: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
This adds in-kernel emulation of the XICS (eXternal Interrupt
Controller Specification) interrupt controller specified by PAPR, for
both HV and PR KVM guests.
This adds a new KVM_CREATE_IRQCHIP_ARGS ioctl, which is like
KVM_CREATE_IRQCHIP in that it indicates that the virtual machine
should use in-kernel interrupt controller emulation, but also takes an
argument struct that contains the type of interrupt controller
architecture and an optional parameter. Currently only one type value
is defined, that which indicates the XICS architecture.
Would the device config API I posted a couple days ago work for you?
The XICS emulation supports up to 1048560 interrupt sources.
Interrupt source numbers below 16 are reserved; 0 is used to mean no
interrupt and 2 is used for IPIs. Internally these are represented in
blocks of 1024, called ICS (interrupt controller source) entities, but
that is not visible to userspace.
Two other new ioctls allow userspace to control the interrupt
sources. The KVM_IRQCHIP_SET_SOURCES ioctl sets the priority,
destination cpu, level/edge sensitivity and pending state of a range
of interrupt sources, creating them if they don't already exist. The
KVM_IRQCHIP_GET_SOURCES ioctl returns that information for a range of
interrupt sources (they are required to already exist).
Why is it userspace's job to control these? If you use KVM_IRQ_PENDING
for interrupt injection, what if there's a race with the user changing
other flags via MMIO? Maybe this isn't an issue with XICS, but this is
being presented as a generic API.
+4.80 KVM_CREATE_IRQCHIP_ARGS
+
+Capability: KVM_CAP_IRQCHIP_ARGS
+Architectures: ppc
Why just ppc?
+struct kvm_irq_sources {
+ __u32 irq;
+ __u32 nr_irqs;
+ __u64 __user *irqbuf;
+};
Please no pointers in UAPI -- this would require a compat wrapper with
32-bit user and 64-bit kernel.
+/* irqbuf entries are laid out like this: */
+#define KVM_IRQ_SERVER_SHIFT 0
+#define KVM_IRQ_SERVER_MASK 0xffffffffULL
+#define KVM_IRQ_PRIORITY_SHIFT 32
+#define KVM_IRQ_PRIORITY_MASK 0xff
+#define KVM_IRQ_LEVEL_SENSITIVE (1ULL << 40)
+#define KVM_IRQ_MASKED (1ULL << 41)
+#define KVM_IRQ_PENDING (1ULL << 42)
What does "server" mean? Do you mean "laid out like this for XICS"?
Let's please have a clean separation between what is generic and what is
implementation-specific.
-Scott
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
