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KVM: PPC: Book3S HV: Use bitmap of active threads rather than count

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Currently, the entry_exit_count field in the kvmppc_vcore struct
contains two 8-bit counts, one of the threads that have started entering
the guest, and one of the threads that have started exiting the guest.
This changes it to an entry_exit_map field which contains two bitmaps
of 8 bits each.  The advantage of doing this is that it gives us a
bitmap of which threads need to be signalled when exiting the guest.
That means that we no longer need to use the trick of setting the
HDEC to 0 to pull the other threads out of the guest, which led in
some cases to a spurious HDEC interrupt on the next guest entry.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Paul Mackerras
2015-03-28 14:21:09 +11:00
committed by Alexander Graf
parent fd6d53b124
commit 7d6c40da19
5 changed files with 44 additions and 49 deletions
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15
arch/powerpc/include/asm/kvm_host.h
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@@ -263,15 +263,15 @@ struct kvm_arch {
/*
* Struct for a virtual core.
* Note: entry_exit_count combines an entry count in the bottom 8 bits
* and an exit count in the next 8 bits. This is so that we can
* atomically increment the entry count iff the exit count is 0
* without taking the lock.
* Note: entry_exit_map combines a bitmap of threads that have entered
* in the bottom 8 bits and a bitmap of threads that have exited in the
* next 8 bits. This is so that we can atomically set the entry bit
* iff the exit map is 0 without taking a lock.
*/
struct kvmppc_vcore {
int n_runnable;
int num_threads;
int entry_exit_count;
int entry_exit_map;
int napping_threads;
int first_vcpuid;
u16 pcpu;
@@ -296,8 +296,9 @@ struct kvmppc_vcore {
ulong conferring_threads;
};
#define VCORE_ENTRY_COUNT(vc) ((vc)->entry_exit_count & 0xff)
#define VCORE_EXIT_COUNT(vc) ((vc)->entry_exit_count >> 8)
#define VCORE_ENTRY_MAP(vc) ((vc)->entry_exit_map & 0xff)
#define VCORE_EXIT_MAP(vc) ((vc)->entry_exit_map >> 8)
#define VCORE_IS_EXITING(vc) (VCORE_EXIT_MAP(vc) != 0)
/* Values for vcore_state */
#define VCORE_INACTIVE 0