[PATCH v3 7/9] 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 <cclaudio at linux.ibm.com>
Signed-off-by: Ram Pai <linuxram at us.ibm.com>
---
 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
+	 */
+	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