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authorAlexander Graf <agraf@suse.de>2013-01-04 18:12:48 +0100
committerAlexander Graf <agraf@suse.de>2013-01-10 13:42:31 +0100
commit1c810636556c8d53a37406b34a64d9b9b0161aa6 (patch)
treeb163d427c9dcff066330d4ac13de529a9831a044 /Documentation/virtual
parent37ecb257f68ce4fb7c7048a1123bbcbbe36d9575 (diff)
KVM: PPC: BookE: Implement EPR exit
The External Proxy Facility in FSL BookE chips allows the interrupt controller to automatically acknowledge an interrupt as soon as a core gets its pending external interrupt delivered. Today, user space implements the interrupt controller, so we need to check on it during such a cycle. This patch implements logic for user space to enable EPR exiting, disable EPR exiting and EPR exiting itself, so that user space can acknowledge an interrupt when an external interrupt has successfully been delivered into the guest vcpu. Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'Documentation/virtual')
-rw-r--r--Documentation/virtual/kvm/api.txt40
1 files changed, 38 insertions, 2 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 4fc2bfcb16d5..a98ed09269d7 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2246,8 +2246,8 @@ executed a memory-mapped I/O instruction which could not be satisfied
by kvm. The 'data' member contains the written data if 'is_write' is
true, and should be filled by application code otherwise.
-NOTE: For KVM_EXIT_IO, KVM_EXIT_MMIO, KVM_EXIT_OSI, KVM_EXIT_DCR
- and KVM_EXIT_PAPR the corresponding
+NOTE: For KVM_EXIT_IO, KVM_EXIT_MMIO, KVM_EXIT_OSI, KVM_EXIT_DCR,
+ KVM_EXIT_PAPR and KVM_EXIT_EPR the corresponding
operations are complete (and guest state is consistent) only after userspace
has re-entered the kernel with KVM_RUN. The kernel side will first finish
incomplete operations and then check for pending signals. Userspace
@@ -2366,6 +2366,25 @@ interrupt for the target subchannel has been dequeued and subchannel_id,
subchannel_nr, io_int_parm and io_int_word contain the parameters for that
interrupt. ipb is needed for instruction parameter decoding.
+ /* KVM_EXIT_EPR */
+ struct {
+ __u32 epr;
+ } epr;
+
+On FSL BookE PowerPC chips, the interrupt controller has a fast patch
+interrupt acknowledge path to the core. When the core successfully
+delivers an interrupt, it automatically populates the EPR register with
+the interrupt vector number and acknowledges the interrupt inside
+the interrupt controller.
+
+In case the interrupt controller lives in user space, we need to do
+the interrupt acknowledge cycle through it to fetch the next to be
+delivered interrupt vector using this exit.
+
+It gets triggered whenever both KVM_CAP_PPC_EPR are enabled and an
+external interrupt has just been delivered into the guest. User space
+should put the acknowledged interrupt vector into the 'epr' field.
+
/* Fix the size of the union. */
char padding[256];
};
@@ -2501,3 +2520,20 @@ handled in-kernel, while the other I/O instructions are passed to userspace.
When this capability is enabled, KVM_EXIT_S390_TSCH will occur on TEST
SUBCHANNEL intercepts.
+
+6.5 KVM_CAP_PPC_EPR
+
+Architectures: ppc
+Parameters: args[0] defines whether the proxy facility is active
+Returns: 0 on success; -1 on error
+
+This capability enables or disables the delivery of interrupts through the
+external proxy facility.
+
+When enabled (args[0] != 0), every time the guest gets an external interrupt
+delivered, it automatically exits into user space with a KVM_EXIT_EPR exit
+to receive the topmost interrupt vector.
+
+When disabled (args[0] == 0), behavior is as if this facility is unsupported.
+
+When this capability is enabled, KVM_EXIT_EPR can occur.