| Message ID | 20201028123512.871051-5-srikar@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Powerpc: Better preemption for shared processor | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch powerpc/merge (8cb17737940b156329cb5210669b9c9b23f4dd56) |
| snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
| snowpatch_ozlabs/build-pmac32 | success | Build succeeded |
| snowpatch_ozlabs/checkpatch | success | |
| snowpatch_ozlabs/needsstable | success | Patch has no Fixes tags |
diff --git a/arch/powerpc/include/asm/paravirt.h b/arch/powerpc/include/asm/paravirt.h index 9362c94fe3aa..edc08f04aef7 100644 --- a/arch/powerpc/include/asm/paravirt.h +++ b/arch/powerpc/include/asm/paravirt.h @@ -10,6 +10,9 @@ #endif #ifdef CONFIG_PPC_SPLPAR +#include <asm/kvm_guest.h> +#include <asm/cputhreads.h> + DECLARE_STATIC_KEY_FALSE(shared_processor); static inline bool is_shared_processor(void) @@ -74,6 +77,21 @@ static inline bool vcpu_is_preempted(int cpu) { if (!is_shared_processor()) return false; + +#ifdef CONFIG_PPC_SPLPAR + if (!is_kvm_guest()) { + int first_cpu = cpu_first_thread_sibling(smp_processor_id()); + + /* + * Preemption can only happen at core granularity. This CPU + * is not preempted if one of the CPU of this core is not + * preempted. + */ + if (cpu_first_thread_sibling(cpu) == first_cpu) + return false; + } +#endif + if (yield_count_of(cpu) & 1) return true; return false;
If its a shared lpar but not a KVM guest, then see if the vCPU is related to the calling vCPU. On PowerVM, only cores can be preempted. So if one vCPU is a non-preempted state, we can decipher that all other vCPUs sharing the same core are in non-preempted state. Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org> Cc: LKML <linux-kernel@vger.kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Nathan Lynch <nathanl@linux.ibm.com> Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Valentin Schneider <valentin.schneider@arm.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Waiman Long <longman@redhat.com> Cc: Phil Auld <pauld@redhat.com> --- arch/powerpc/include/asm/paravirt.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)