[PATCH 30/56] KVM: PPC: bookehv: disable MAS register updates early

Alexander Graf
2012-03-15T12:10:59Z

We need to make sure that no MAS updates happen automatically while we
have the guest MAS registers loaded. So move the disabling code a bit
higher up so that it covers the full time we have guest values in MAS
registers.

The race this patch fixes should never occur, but it makes the code a
bit more logical to do it this way around.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
arch/powerpc/kvm/bookehv_interrupts.S | 10 ++++++----
1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kvm/bookehv_interrupts.S b/arch/powerpc/kvm/bookehv_interrupts.S
index dfa606d..3a1db90 100644
--- a/arch/powerpc/kvm/bookehv_interrupts.S
+++ b/arch/powerpc/kvm/bookehv_interrupts.S
@@ -358,6 +358,7 @@ _GLOBAL(kvmppc_resume_host)
mtspr SPRN_MAS4, r6
stw r5, VCPU_SHARED_MAS7_3+0(r11)
mtspr SPRN_MAS6, r8
+ /* Enable MAS register updates via exception */
mfspr r3, SPRN_EPCR
rlwinm r3, r3, 0, ~SPRN_EPCR_DMIUH
mtspr SPRN_EPCR, r3
@@ -515,6 +516,11 @@ lightweight_exit:
mtspr SPRN_PID, r3

PPC_LL r11, VCPU_SHARED(r4)
+ /* Disable MAS register updates via exception */
+ mfspr r3, SPRN_EPCR
+ oris r3, r3, SPRN_EPCR_DMIUH@h
+ mtspr SPRN_EPCR, r3
+ isync
/* Save host mas4 and mas6 and load guest MAS registers */
mfspr r3, SPRN_MAS4
stw r3, VCPU_HOST_MAS4(r4)
@@ -538,10 +544,6 @@ lightweight_exit:
lwz r5, VCPU_SHARED_MAS7_3+0(r11)
mtspr SPRN_MAS6, r3
mtspr SPRN_MAS7, r5
- /* Disable MAS register updates via exception */
- mfspr r3, SPRN_EPCR
- oris r3, r3, SPRN_EPCR_DMIUH@h
- mtspr SPRN_EPCR, r3

/*
* Host interrupt handlers may have clobbered these guest-readable
--
1.6.0.2