Excerpts from Nicholas Piggin's message of May 23, 2021 10:21 pm:
quoted hunk ↗ jump to hunk
Similar to commit 25edcc50d76c ("KVM: PPC: Book3S HV: Save and restore
FSCR in the P9 path"), ensure the P7/8 path saves and restores the host
FSCR. The logic explained in that patch actually applies there to the
old path well: a context switch can be made before kvmppc_vcpu_run_hv
restores the host FSCR and returns.
Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 5e634db4809b..2b98e710c7a1 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -44,7 +44,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
#define NAPPING_UNSPLIT 3
/* Stack frame offsets for kvmppc_hv_entry */
-#define SFS 208
+#define SFS 216
#define STACK_SLOT_TRAP (SFS-4)
#define STACK_SLOT_SHORT_PATH (SFS-8)
#define STACK_SLOT_TID (SFS-16)
@@ -59,8 +59,9 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
#define STACK_SLOT_UAMOR (SFS-88)
#define STACK_SLOT_DAWR1 (SFS-96)
#define STACK_SLOT_DAWRX1 (SFS-104)
+#define STACK_SLOT_FSCR (SFS-112)
/* the following is used by the P9 short path */
-#define STACK_SLOT_NVGPRS (SFS-152) /* 18 gprs */
+#define STACK_SLOT_NVGPRS (SFS-160) /* 18 gprs */
Actually, hmm.. this is wrong because nvgprs are subtracted from
this offset. But then I can't work out why 95a6432ce9038 raised
SFS from 160 to 208.
Thanks,
Nick