Re: [PATCH] KVM: PPC: Book3S HV: Save host FSCR in the P7/8 path
From: Fabiano Rosas <hidden>
Date: 2021-05-24 12:50:31
Nicholas Piggin [off-list ref] writes:
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 */ /* * Call kvmppc_hv_entry in real mode.@@ -686,6 +687,8 @@ BEGIN_FTR_SECTION std r6, STACK_SLOT_DAWR0(r1) std r7, STACK_SLOT_DAWRX0(r1) std r8, STACK_SLOT_IAMR(r1) + mfspr r5, SPRN_FSCR + std r5, STACK_SLOT_FSCR(r1) END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) BEGIN_FTR_SECTION mfspr r6, SPRN_DAWR1@@ -1663,6 +1666,10 @@ FTR_SECTION_ELSE ld r7, STACK_SLOT_HFSCR(r1) mtspr SPRN_HFSCR, r7 ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300) +BEGIN_FTR_SECTION + ld r5, STACK_SLOT_FSCR(r1) + mtspr SPRN_FSCR, r5 +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) /* * Restore various registers to 0, where non-zero values * set by the guest could disrupt the host.
So it seems this line in kvmppc_vcpu_run_hv loses its purpose now?
do{
(...)
} while (is_kvmppc_resume_guest(r));
/* Restore userspace EBB and other register values */
if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
mtspr(SPRN_EBBHR, ebb_regs[0]);
mtspr(SPRN_EBBRR, ebb_regs[1]);
mtspr(SPRN_BESCR, ebb_regs[2]);
mtspr(SPRN_TAR, user_tar);
---> mtspr(SPRN_FSCR, current->thread.fscr);
}