Nicholas Piggin <npig...@gmail.com> writes:
> 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 <npig...@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);
}
