KVM: PPC: Book3S HV: Save host FSCR in the P7/8 path

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.

Now both the p9 and the p7/8 paths now save and restore their FSCR, it
no longer needs to be restored at the end of kvmppc_vcpu_run_hv

Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs")
Cc: stable@vger.kernel.org # v3.14+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210526125851.3436735-1-npiggin@gmail.com

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 28a80d2..1372849 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4455,7 +4455,6 @@ static int kvmppc_vcpu_run_hv(struct kvm_vcpu *vcpu)
                mtspr(SPRN_EBBRR, ebb_regs[1]);
                mtspr(SPRN_BESCR, ebb_regs[2]);
                mtspr(SPRN_TAR, user_tar);
-               mtspr(SPRN_FSCR, current->thread.fscr);
        }
        mtspr(SPRN_VRSAVE, user_vrsave);
 

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 5e634db..004f0d4 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -59,6 +59,7 @@ 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 */
 
@@ -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.