- Add another case where msgsync is required.
- Required barrier sequence for global doorbells is msgsync ; lwsync
- POWER9 DD1 has a different barrier sequence that we don't implement,
  so remove

When msgsnd is used for IPIs to other cores, msgsync must be executed by
the target to order stores performed on the source before its msgsnd
(provided the source executes the appropriate sync).

Fixes: 1704a81ccebc ("KVM: PPC: Book3S HV: Use msgsnd for IPIs to other cores 
on POWER9")
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
 arch/powerpc/kvm/book3s_hv_rmhandlers.S | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S 
b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 663a4a861e7f..90c07421eba2 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1300,6 +1300,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
        bne     3f
 BEGIN_FTR_SECTION
        PPC_MSGSYNC
+       lwsync
 END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
        lbz     r0, HSTATE_HOST_IPI(r13)
        cmpwi   r0, 0
@@ -2761,6 +2762,10 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
        PPC_MSGCLR(6)
        /* see if it's a host IPI */
        li      r3, 1
+BEGIN_FTR_SECTION
+       PPC_MSGSYNC
+       lwsync
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
        lbz     r0, HSTATE_HOST_IPI(r13)
        cmpwi   r0, 0
        bnelr
-- 
2.13.3

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