[PATCH v4 6/8] KVM: PPC: Ultravisor: Restrict LDBAR access

[Claudio Carvalho]

When the ultravisor firmware is available, it takes control over the
LDBAR register. In this case, thread-imc updates and save/restore
operations on the LDBAR register are handled by ultravisor.

Signed-off-by: Claudio Carvalho <cclau...@linux.ibm.com>
Reviewed-by: Ram Pai <linux...@us.ibm.com>
Reviewed-by: Ryan Grimm <gr...@linux.ibm.com>
Acked-by: Madhavan Srinivasan <ma...@linux.vnet.ibm.com>
Acked-by: Paul Mackerras <pau...@ozlabs.org>
---
 arch/powerpc/kvm/book3s_hv_rmhandlers.S   | 2 ++
 arch/powerpc/platforms/powernv/idle.c     | 6 ++++--
 arch/powerpc/platforms/powernv/opal-imc.c | 4 ++++
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S 
b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index f9b2620fbecd..cffb365d9d02 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -375,8 +375,10 @@ BEGIN_FTR_SECTION
        mtspr   SPRN_RPR, r0
        ld      r0, KVM_SPLIT_PMMAR(r6)
        mtspr   SPRN_PMMAR, r0
+BEGIN_FW_FTR_SECTION_NESTED(70)
        ld      r0, KVM_SPLIT_LDBAR(r6)
        mtspr   SPRN_LDBAR, r0
+END_FW_FTR_SECTION_NESTED(FW_FEATURE_ULTRAVISOR, 0, 70)
        isync
 FTR_SECTION_ELSE
        /* On P9 we use the split_info for coordinating LPCR changes */
diff --git a/arch/powerpc/platforms/powernv/idle.c 
b/arch/powerpc/platforms/powernv/idle.c
index 77f2e0a4ee37..5593a2d55959 100644
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -679,7 +679,8 @@ static unsigned long power9_idle_stop(unsigned long psscr, 
bool mmu_on)
                sprs.ptcr       = mfspr(SPRN_PTCR);
                sprs.rpr        = mfspr(SPRN_RPR);
                sprs.tscr       = mfspr(SPRN_TSCR);
-               sprs.ldbar      = mfspr(SPRN_LDBAR);
+               if (!firmware_has_feature(FW_FEATURE_ULTRAVISOR))
+                       sprs.ldbar      = mfspr(SPRN_LDBAR);
 
                sprs_saved = true;
 
@@ -762,7 +763,8 @@ static unsigned long power9_idle_stop(unsigned long psscr, 
bool mmu_on)
        mtspr(SPRN_PTCR,        sprs.ptcr);
        mtspr(SPRN_RPR,         sprs.rpr);
        mtspr(SPRN_TSCR,        sprs.tscr);
-       mtspr(SPRN_LDBAR,       sprs.ldbar);
+       if (!firmware_has_feature(FW_FEATURE_ULTRAVISOR))
+               mtspr(SPRN_LDBAR,       sprs.ldbar);
 
        if (pls >= pnv_first_tb_loss_level) {
                /* TB loss */
diff --git a/arch/powerpc/platforms/powernv/opal-imc.c 
b/arch/powerpc/platforms/powernv/opal-imc.c
index 1b6932890a73..5fe2d4526cbc 100644
--- a/arch/powerpc/platforms/powernv/opal-imc.c
+++ b/arch/powerpc/platforms/powernv/opal-imc.c
@@ -254,6 +254,10 @@ static int opal_imc_counters_probe(struct platform_device 
*pdev)
        bool core_imc_reg = false, thread_imc_reg = false;
        u32 type;
 
+       /* Disable IMC devices, when Ultravisor is enabled. */
+       if (firmware_has_feature(FW_FEATURE_ULTRAVISOR))
+               return -EACCES;
+
        /*
         * Check whether this is kdump kernel. If yes, force the engines to
         * stop and return.
-- 
2.20.1