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KVM: PPC: BookE: Implement EPR exit

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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 <[email protected]>
This commit is contained in:
Alexander Graf 2013-01-04 18:12:48 +01:00
commit 1c81063655
7 changed files with 79 additions and 3 deletions
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40
Documentation/virtual/kvm/api.txt
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@ -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.