POWER9 with the DAWR disabled causes problems for partition
migration. Either we have to fail the migration (since we lose the
DAWR) or we silently drop the DAWR and allow the migration to pass.
This patch does the latter and allows the migration to pass (at the
cost of silently losing the DAWR). This is not ideal but hopefully the
best overall solution. This approach has been acked by Paulus.
With this patch kvmppc_set_one_reg() will store the DAWR in the vcpu
but won't actually set it on POWER9 hardware.
Signed-off-by: Michael Neuling <mi...@neuling.org>
---
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 13e23a5275..8ba20b11ba 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -886,8 +886,14 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S)
ld r6, VCPU_DAWRX(r4)
ld r7, VCPU_CIABR(r4)
ld r8, VCPU_TAR(r4)
+ /*
+ * Handle broken DAWR case by not writing it. This means we
+ * can still store the DAWR register for migration.
+ */
+BEGIN_FTR_SECTION
mtspr SPRN_DAWR, r5
mtspr SPRN_DAWRX, r6
+END_FTR_SECTION_IFSET(CPU_FTR_DAWR)
mtspr SPRN_CIABR, r7
mtspr SPRN_TAR, r8
ld r5, VCPU_IC(r4)
@@ -1834,6 +1840,10 @@ BEGIN_FTR_SECTION
ld r6, STACK_SLOT_DAWR(r1)
ld r7, STACK_SLOT_DAWRX(r1)
mtspr SPRN_CIABR, r5
+ /*
+ * If the DAWR doesn't work, it's ok to write these here as
+ * this value should always be zero
+ */
mtspr SPRN_DAWR, r6
mtspr SPRN_DAWRX, r7
END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
--
2.14.1
