diff options
| author | Nicholas Piggin <npiggin@gmail.com> | 2021-11-23 19:51:43 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-11-24 21:08:57 +1100 |
| commit | 9581991a60817abe311c2581ae4554b28bfa32f1 (patch) | |
| tree | c5766a37f856a44f1077b87093771c0d9b3e87ad | |
| parent | 4ebbd075bcde7884e078d4360510b989f559bfec (diff) | |
| download | lwn-9581991a60817abe311c2581ae4554b28bfa32f1.tar.gz lwn-9581991a60817abe311c2581ae4554b28bfa32f1.zip | |
KVM: PPC: Book3S HV P9: Use large decrementer for HDEC
On processors that don't suppress the HDEC exceptions when LPCR[HDICE]=0,
this could help reduce needless guest exits due to leftover exceptions on
entering the guest.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211123095231.1036501-6-npiggin@gmail.com
| -rw-r--r-- | arch/powerpc/include/asm/time.h | 2 | ||||
| -rw-r--r-- | arch/powerpc/kernel/time.c | 1 | ||||
| -rw-r--r-- | arch/powerpc/kvm/book3s_hv_p9_entry.c | 3 |
3 files changed, 5 insertions, 1 deletions
diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h index fd09b4797fd7..69b6be617772 100644 --- a/arch/powerpc/include/asm/time.h +++ b/arch/powerpc/include/asm/time.h @@ -18,6 +18,8 @@ #include <asm/vdso/timebase.h> /* time.c */ +extern u64 decrementer_max; + extern unsigned long tb_ticks_per_jiffy; extern unsigned long tb_ticks_per_usec; extern unsigned long tb_ticks_per_sec; diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 374950afec2f..2769d565f842 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -88,6 +88,7 @@ static struct clocksource clocksource_timebase = { #define DECREMENTER_DEFAULT_MAX 0x7FFFFFFF u64 decrementer_max = DECREMENTER_DEFAULT_MAX; +EXPORT_SYMBOL_GPL(decrementer_max); /* for KVM HDEC */ static int decrementer_set_next_event(unsigned long evt, struct clock_event_device *dev); diff --git a/arch/powerpc/kvm/book3s_hv_p9_entry.c b/arch/powerpc/kvm/book3s_hv_p9_entry.c index 961b3d70483c..0ff9ddb5e7ca 100644 --- a/arch/powerpc/kvm/book3s_hv_p9_entry.c +++ b/arch/powerpc/kvm/book3s_hv_p9_entry.c @@ -504,7 +504,8 @@ tm_return_to_guest: vc->tb_offset_applied = 0; } - mtspr(SPRN_HDEC, 0x7fffffff); + /* HDEC must be at least as large as DEC, so decrementer_max fits */ + mtspr(SPRN_HDEC, decrementer_max); save_clear_guest_mmu(kvm, vcpu); switch_mmu_to_host(kvm, host_pidr); |