Re: [PATCH v3 7/9] KVM: PPC: Ultravisor: Restrict LDBAR access

On 6/7/19 1:48 AM, Madhavan Srinivasan wrote:

On 06/06/19 11:06 PM, Claudio Carvalho wrote:

quoted

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 <redacted>
Signed-off-by: Ram Pai <redacted>
---
  arch/powerpc/kvm/book3s_hv_rmhandlers.S   | 2 ++
  arch/powerpc/platforms/powernv/idle.c     | 6 ++++--
  arch/powerpc/platforms/powernv/opal-imc.c | 7 +++++++
  3 files changed, 13 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 c9133f7908ca..fd62435e3267 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..e9b641d313fb 100644

--- a/arch/powerpc/platforms/powernv/opal-imc.c
+++ b/arch/powerpc/platforms/powernv/opal-imc.c

@@ -254,6 +254,13 @@ static int opal_imc_counters_probe(struct

platform_device *pdev)
      bool core_imc_reg = false, thread_imc_reg = false;
      u32 type;

+    /*
+     * When the Ultravisor is enabled, it is responsible for thread-imc
+     * updates
+     */

Would prefer the comment to be "Disable IMC devices, when Ultravisor is
enabled"
Rest looks good.
Acked-by: Madhavan Srinivasan <redacted>

Thanks Maddy. I applied that change to the next version.

Claudio

quoted

+    if (firmware_has_feature(FW_FEATURE_ULTRAVISOR))
+        return -EACCES;
+
      /*
       * Check whether this is kdump kernel. If yes, force the engines to
       * stop and return.