This register controls supervisor SPR modifications, and as such is only
relevant for KVM. KVM always sets AMOR to ~0 on guest entry, and never
restores it coming back out to the host, so it can be kept constant and
avoid the mtSPR in KVM guest entry.

Reviewed-by: Fabiano Rosas <faro...@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
 arch/powerpc/kernel/cpu_setup_power.c    |  8 ++++++++
 arch/powerpc/kernel/dt_cpu_ftrs.c        |  2 ++
 arch/powerpc/kvm/book3s_hv_p9_entry.c    |  2 --
 arch/powerpc/kvm/book3s_hv_rmhandlers.S  |  2 --
 arch/powerpc/mm/book3s64/radix_pgtable.c | 15 ---------------
 arch/powerpc/platforms/powernv/idle.c    |  8 +++-----
 6 files changed, 13 insertions(+), 24 deletions(-)

diff --git a/arch/powerpc/kernel/cpu_setup_power.c 
b/arch/powerpc/kernel/cpu_setup_power.c
index 3cca88ee96d7..a29dc8326622 100644
--- a/arch/powerpc/kernel/cpu_setup_power.c
+++ b/arch/powerpc/kernel/cpu_setup_power.c
@@ -137,6 +137,7 @@ void __setup_cpu_power7(unsigned long offset, struct 
cpu_spec *t)
                return;
 
        mtspr(SPRN_LPID, 0);
+       mtspr(SPRN_AMOR, ~0);
        mtspr(SPRN_PCR, PCR_MASK);
        init_LPCR_ISA206(mfspr(SPRN_LPCR), LPCR_LPES1 >> LPCR_LPES_SH);
 }
@@ -150,6 +151,7 @@ void __restore_cpu_power7(void)
                return;
 
        mtspr(SPRN_LPID, 0);
+       mtspr(SPRN_AMOR, ~0);
        mtspr(SPRN_PCR, PCR_MASK);
        init_LPCR_ISA206(mfspr(SPRN_LPCR), LPCR_LPES1 >> LPCR_LPES_SH);
 }
@@ -164,6 +166,7 @@ void __setup_cpu_power8(unsigned long offset, struct 
cpu_spec *t)
                return;
 
        mtspr(SPRN_LPID, 0);
+       mtspr(SPRN_AMOR, ~0);
        mtspr(SPRN_PCR, PCR_MASK);
        init_LPCR_ISA206(mfspr(SPRN_LPCR) | LPCR_PECEDH, 0); /* LPES = 0 */
        init_HFSCR();
@@ -184,6 +187,7 @@ void __restore_cpu_power8(void)
                return;
 
        mtspr(SPRN_LPID, 0);
+       mtspr(SPRN_AMOR, ~0);
        mtspr(SPRN_PCR, PCR_MASK);
        init_LPCR_ISA206(mfspr(SPRN_LPCR) | LPCR_PECEDH, 0); /* LPES = 0 */
        init_HFSCR();
@@ -202,6 +206,7 @@ void __setup_cpu_power9(unsigned long offset, struct 
cpu_spec *t)
        mtspr(SPRN_PSSCR, 0);
        mtspr(SPRN_LPID, 0);
        mtspr(SPRN_PID, 0);
+       mtspr(SPRN_AMOR, ~0);
        mtspr(SPRN_PCR, PCR_MASK);
        init_LPCR_ISA300((mfspr(SPRN_LPCR) | LPCR_PECEDH | LPCR_PECE_HVEE |\
                         LPCR_HVICE | LPCR_HEIC) & ~(LPCR_UPRT | LPCR_HR), 0);
@@ -223,6 +228,7 @@ void __restore_cpu_power9(void)
        mtspr(SPRN_PSSCR, 0);
        mtspr(SPRN_LPID, 0);
        mtspr(SPRN_PID, 0);
+       mtspr(SPRN_AMOR, ~0);
        mtspr(SPRN_PCR, PCR_MASK);
        init_LPCR_ISA300((mfspr(SPRN_LPCR) | LPCR_PECEDH | LPCR_PECE_HVEE |\
                         LPCR_HVICE | LPCR_HEIC) & ~(LPCR_UPRT | LPCR_HR), 0);
@@ -242,6 +248,7 @@ void __setup_cpu_power10(unsigned long offset, struct 
cpu_spec *t)
        mtspr(SPRN_PSSCR, 0);
        mtspr(SPRN_LPID, 0);
        mtspr(SPRN_PID, 0);
+       mtspr(SPRN_AMOR, ~0);
        mtspr(SPRN_PCR, PCR_MASK);
        init_LPCR_ISA300((mfspr(SPRN_LPCR) | LPCR_PECEDH | LPCR_PECE_HVEE |\
                         LPCR_HVICE | LPCR_HEIC) & ~(LPCR_UPRT | LPCR_HR), 0);
@@ -264,6 +271,7 @@ void __restore_cpu_power10(void)
        mtspr(SPRN_PSSCR, 0);
        mtspr(SPRN_LPID, 0);
        mtspr(SPRN_PID, 0);
+       mtspr(SPRN_AMOR, ~0);
        mtspr(SPRN_PCR, PCR_MASK);
        init_LPCR_ISA300((mfspr(SPRN_LPCR) | LPCR_PECEDH | LPCR_PECE_HVEE |\
                         LPCR_HVICE | LPCR_HEIC) & ~(LPCR_UPRT | LPCR_HR), 0);
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c 
b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 358aee7c2d79..0a6b36b4bda8 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -80,6 +80,7 @@ static void __restore_cpu_cpufeatures(void)
        mtspr(SPRN_LPCR, system_registers.lpcr);
        if (hv_mode) {
                mtspr(SPRN_LPID, 0);
+               mtspr(SPRN_AMOR, ~0);
                mtspr(SPRN_HFSCR, system_registers.hfscr);
                mtspr(SPRN_PCR, system_registers.pcr);
        }
@@ -216,6 +217,7 @@ static int __init feat_enable_hv(struct dt_cpu_feature *f)
        }
 
        mtspr(SPRN_LPID, 0);
+       mtspr(SPRN_AMOR, ~0);
 
        lpcr = mfspr(SPRN_LPCR);
        lpcr &=  ~LPCR_LPES0; /* HV external interrupts */
diff --git a/arch/powerpc/kvm/book3s_hv_p9_entry.c 
b/arch/powerpc/kvm/book3s_hv_p9_entry.c
index bd8cf0a65ce8..a7f63082b4e3 100644
--- a/arch/powerpc/kvm/book3s_hv_p9_entry.c
+++ b/arch/powerpc/kvm/book3s_hv_p9_entry.c
@@ -286,8 +286,6 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 
time_limit, unsigned long lpc
        mtspr(SPRN_SPRG2, vcpu->arch.shregs.sprg2);
        mtspr(SPRN_SPRG3, vcpu->arch.shregs.sprg3);
 
-       mtspr(SPRN_AMOR, ~0UL);
-
        local_paca->kvm_hstate.in_guest = KVM_GUEST_MODE_HV_P9;
 
        /*
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S 
b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 90484425a1e6..a5a2ef1c70ec 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -772,10 +772,8 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S)
        /* Restore AMR and UAMOR, set AMOR to all 1s */
        ld      r5,VCPU_AMR(r4)
        ld      r6,VCPU_UAMOR(r4)
-       li      r7,-1
        mtspr   SPRN_AMR,r5
        mtspr   SPRN_UAMOR,r6
-       mtspr   SPRN_AMOR,r7
 
        /* Restore state of CTRL run bit; assume 1 on entry */
        lwz     r5,VCPU_CTRL(r4)
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c 
b/arch/powerpc/mm/book3s64/radix_pgtable.c
index ae20add7954a..1e48c55e3e5d 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -572,18 +572,6 @@ void __init radix__early_init_devtree(void)
        return;
 }
 
-static void radix_init_amor(void)
-{
-       /*
-       * In HV mode, we init AMOR (Authority Mask Override Register) so that
-       * the hypervisor and guest can setup IAMR (Instruction Authority Mask
-       * Register), enable key 0 and set it to 1.
-       *
-       * AMOR = 0b1100 .... 0000 (Mask for key 0 is 11)
-       */
-       mtspr(SPRN_AMOR, (3ul << 62));
-}
-
 void __init radix__early_init_mmu(void)
 {
        unsigned long lpcr;
@@ -644,7 +632,6 @@ void __init radix__early_init_mmu(void)
                lpcr = mfspr(SPRN_LPCR);
                mtspr(SPRN_LPCR, lpcr | LPCR_UPRT | LPCR_HR);
                radix_init_partition_table();
-               radix_init_amor();
        } else {
                radix_init_pseries();
        }
@@ -668,8 +655,6 @@ void radix__early_init_mmu_secondary(void)
 
                set_ptcr_when_no_uv(__pa(partition_tb) |
                                    (PATB_SIZE_SHIFT - 12));
-
-               radix_init_amor();
        }
 
        radix__switch_mmu_context(NULL, &init_mm);
diff --git a/arch/powerpc/platforms/powernv/idle.c 
b/arch/powerpc/platforms/powernv/idle.c
index 86e787502e42..3bc84e2fe064 100644
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -306,8 +306,8 @@ struct p7_sprs {
        /* per thread SPRs that get lost in shallow states */
        u64 amr;
        u64 iamr;
-       u64 amor;
        u64 uamor;
+       /* amor is restored to constant ~0 */
 };
 
 static unsigned long power7_idle_insn(unsigned long type)
@@ -378,7 +378,6 @@ static unsigned long power7_idle_insn(unsigned long type)
        if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
                sprs.amr        = mfspr(SPRN_AMR);
                sprs.iamr       = mfspr(SPRN_IAMR);
-               sprs.amor       = mfspr(SPRN_AMOR);
                sprs.uamor      = mfspr(SPRN_UAMOR);
        }
 
@@ -397,7 +396,7 @@ static unsigned long power7_idle_insn(unsigned long type)
                         */
                        mtspr(SPRN_AMR,         sprs.amr);
                        mtspr(SPRN_IAMR,        sprs.iamr);
-                       mtspr(SPRN_AMOR,        sprs.amor);
+                       mtspr(SPRN_AMOR,        ~0);
                        mtspr(SPRN_UAMOR,       sprs.uamor);
                }
        }
@@ -686,7 +685,6 @@ static unsigned long power9_idle_stop(unsigned long psscr)
 
        sprs.amr        = mfspr(SPRN_AMR);
        sprs.iamr       = mfspr(SPRN_IAMR);
-       sprs.amor       = mfspr(SPRN_AMOR);
        sprs.uamor      = mfspr(SPRN_UAMOR);
 
        srr1 = isa300_idle_stop_mayloss(psscr);         /* go idle */
@@ -707,7 +705,7 @@ static unsigned long power9_idle_stop(unsigned long psscr)
                 */
                mtspr(SPRN_AMR,         sprs.amr);
                mtspr(SPRN_IAMR,        sprs.iamr);
-               mtspr(SPRN_AMOR,        sprs.amor);
+               mtspr(SPRN_AMOR,        ~0);
                mtspr(SPRN_UAMOR,       sprs.uamor);
 
                /*
-- 
2.23.0

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