| Message ID | 20130906032435.GK29710@iris.ozlabs.ibm.com |
|---|---|
| State | New, archived |
| Headers | show |
On 05.09.2013, at 22:24, Paul Mackerras wrote: > The yield count in the VPA is supposed to be incremented every time > we enter the guest, and every time we exit the guest, so that its > value is even when the vcpu is running in the guest and odd when it > isn't. However, it's currently possible that we increment the yield > count on the way into the guest but then find that other CPU threads > are already exiting the guest, so we go back to nap mode via the > secondary_too_late label. In this situation we don't increment the > yield count again, breaking the relationship between the LSB of the > count and whether the vcpu is in the guest. > > To fix this, we move the increment of the yield count to a point > after we have checked whether other CPU threads are exiting. > > Signed-off-by: Paul Mackerras <paulus@samba.org> Thanks, applied to kvm-ppc-queue. Alex -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index 01515b6..31030f3 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -401,16 +401,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_206) /* Save R1 in the PACA */ std r1, HSTATE_HOST_R1(r13) - /* Increment yield count if they have a VPA */ - ld r3, VCPU_VPA(r4) - cmpdi r3, 0 - beq 25f - lwz r5, LPPACA_YIELDCOUNT(r3) - addi r5, r5, 1 - stw r5, LPPACA_YIELDCOUNT(r3) - li r6, 1 - stb r6, VCPU_VPA_DIRTY(r4) -25: /* Load up DAR and DSISR */ ld r5, VCPU_DAR(r4) lwz r6, VCPU_DSISR(r4) @@ -525,6 +515,16 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_201) mtspr SPRN_RMOR,r8 isync + /* Increment yield count if they have a VPA */ + ld r3, VCPU_VPA(r4) + cmpdi r3, 0 + beq 25f + lwz r5, LPPACA_YIELDCOUNT(r3) + addi r5, r5, 1 + stw r5, LPPACA_YIELDCOUNT(r3) + li r6, 1 + stb r6, VCPU_VPA_DIRTY(r4) +25: /* Check if HDEC expires soon */ mfspr r3,SPRN_HDEC cmpwi r3,10
The yield count in the VPA is supposed to be incremented every time we enter the guest, and every time we exit the guest, so that its value is even when the vcpu is running in the guest and odd when it isn't. However, it's currently possible that we increment the yield count on the way into the guest but then find that other CPU threads are already exiting the guest, so we go back to nap mode via the secondary_too_late label. In this situation we don't increment the yield count again, breaking the relationship between the LSB of the count and whether the vcpu is in the guest. To fix this, we move the increment of the yield count to a point after we have checked whether other CPU threads are exiting. Signed-off-by: Paul Mackerras <paulus@samba.org> --- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-)