Subject: [PATCH 7/7] powerpc/64s: advertise hardware link stack flush

From: Nicholas Piggin <[email-masked]>
Date: Tue, 9 Jun 2020 17:06:10 +1000

For testing only at the moment, firmware does not define these bits.
---
 arch/powerpc/include/asm/hvcall.h         | 1 +
 arch/powerpc/include/uapi/asm/kvm.h       | 1 +
 arch/powerpc/kvm/powerpc.c                | 9 +++++++--
 arch/powerpc/platforms/powernv/setup.c    | 3 +++
 arch/powerpc/platforms/pseries/setup.c    | 3 +++
 tools/arch/powerpc/include/uapi/asm/kvm.h | 1 +
 6 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
index e90c073e437e..a92a07c89b6f 100644
--- a/arch/powerpc/include/asm/hvcall.h
+++ b/arch/powerpc/include/asm/hvcall.h
@@ -373,6 +373,7 @@
 #define H_CPU_CHAR_THREAD_RECONFIG_CTRL	(1ull << 57) // IBM bit 6
 #define H_CPU_CHAR_COUNT_CACHE_DISABLED	(1ull << 56) // IBM bit 7
 #define H_CPU_CHAR_BCCTR_FLUSH_ASSIST	(1ull << 54) // IBM bit 9
+#define H_CPU_CHAR_BCCTR_LINK_FLUSH_ASSIST	(1ull << 53) // IBM bit 10
 
 #define H_CPU_BEHAV_FAVOUR_SECURITY	(1ull << 63) // IBM bit 0
 #define H_CPU_BEHAV_L1D_FLUSH_PR	(1ull << 62) // IBM bit 1
diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
index 264e266a85bf..dd229d5f46ee 100644
--- a/arch/powerpc/include/uapi/asm/kvm.h
+++ b/arch/powerpc/include/uapi/asm/kvm.h
@@ -464,6 +464,7 @@ struct kvm_ppc_cpu_char {
 #define KVM_PPC_CPU_CHAR_MTTRIG_THR_RECONF	(1ULL << 57)
 #define KVM_PPC_CPU_CHAR_COUNT_CACHE_DIS	(1ULL << 56)
 #define KVM_PPC_CPU_CHAR_BCCTR_FLUSH_ASSIST	(1ull << 54)
+#define KVM_PPC_CPU_CHAR_BCCTR_LINK_FLUSH_ASSIST	(1ull << 53)
 
 #define KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY	(1ULL << 63)
 #define KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR		(1ULL << 62)
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 27ccff612903..fa981ee09dec 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -2221,7 +2221,8 @@ static int pseries_get_cpu_char(struct kvm_ppc_cpu_char *cp)
 			KVM_PPC_CPU_CHAR_BR_HINT_HONOURED |
 			KVM_PPC_CPU_CHAR_MTTRIG_THR_RECONF |
 			KVM_PPC_CPU_CHAR_COUNT_CACHE_DIS |
-			KVM_PPC_CPU_CHAR_BCCTR_FLUSH_ASSIST;
+			KVM_PPC_CPU_CHAR_BCCTR_FLUSH_ASSIST |
+			KVM_PPC_CPU_CHAR_BCCTR_LINK_FLUSH_ASSIST;
 		cp->behaviour_mask = KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY |
 			KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR |
 			KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR |
@@ -2287,13 +2288,17 @@ static int kvmppc_get_cpu_char(struct kvm_ppc_cpu_char *cp)
 		if (have_fw_feat(fw_features, "enabled",
 				 "fw-count-cache-flush-bcctr2,0,0"))
 			cp->character |= KVM_PPC_CPU_CHAR_BCCTR_FLUSH_ASSIST;
+		if (have_fw_feat(fw_features, "enabled",
+				 "fw-link-stack-flush-bcctr2,0,0"))
+			cp->character |= KVM_PPC_CPU_CHAR_BCCTR_LINK_FLUSH_ASSIST;
 		cp->character_mask = KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31 |
 			KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED |
 			KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30 |
 			KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2 |
 			KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV |
 			KVM_PPC_CPU_CHAR_COUNT_CACHE_DIS |
-			KVM_PPC_CPU_CHAR_BCCTR_FLUSH_ASSIST;
+			KVM_PPC_CPU_CHAR_BCCTR_FLUSH_ASSIST |
+			KVM_PPC_CPU_CHAR_BCCTR_LINK_FLUSH_ASSIST;
 
 		if (have_fw_feat(fw_features, "enabled",
 				 "speculation-policy-favor-security"))
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index 3bc188da82ba..1a06d3b4c0a9 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -78,6 +78,9 @@ static void init_fw_feat_flags(struct device_node *np)
 	if (fw_feature_is("enabled", "fw-count-cache-flush-bcctr2,0,0", np))
 		security_ftr_set(SEC_FTR_BCCTR_FLUSH_ASSIST);
 
+	if (fw_feature_is("enabled", "fw-link-stack-flush-bcctr2,0,0", np))
+		security_ftr_set(SEC_FTR_BCCTR_LINK_FLUSH_ASSIST);
+
 	if (fw_feature_is("enabled", "needs-count-cache-flush-on-context-switch", np))
 		security_ftr_set(SEC_FTR_FLUSH_COUNT_CACHE);
 
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 64d18f4bf093..70c9264f23c5 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -517,6 +517,9 @@ static void init_cpu_char_feature_flags(struct h_cpu_char_result *result)
 	if (result->character & H_CPU_CHAR_BCCTR_FLUSH_ASSIST)
 		security_ftr_set(SEC_FTR_BCCTR_FLUSH_ASSIST);
 
+	if (result->character & H_CPU_CHAR_BCCTR_LINK_FLUSH_ASSIST)
+		security_ftr_set(SEC_FTR_BCCTR_LINK_FLUSH_ASSIST);
+
 	if (result->behaviour & H_CPU_BEHAV_FLUSH_COUNT_CACHE)
 		security_ftr_set(SEC_FTR_FLUSH_COUNT_CACHE);
 
diff --git a/tools/arch/powerpc/include/uapi/asm/kvm.h b/tools/arch/powerpc/include/uapi/asm/kvm.h
index 264e266a85bf..dd229d5f46ee 100644
--- a/tools/arch/powerpc/include/uapi/asm/kvm.h
+++ b/tools/arch/powerpc/include/uapi/asm/kvm.h
@@ -464,6 +464,7 @@ struct kvm_ppc_cpu_char {
 #define KVM_PPC_CPU_CHAR_MTTRIG_THR_RECONF	(1ULL << 57)
 #define KVM_PPC_CPU_CHAR_COUNT_CACHE_DIS	(1ULL << 56)
 #define KVM_PPC_CPU_CHAR_BCCTR_FLUSH_ASSIST	(1ull << 54)
+#define KVM_PPC_CPU_CHAR_BCCTR_LINK_FLUSH_ASSIST	(1ull << 53)
 
 #define KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY	(1ULL << 63)
 #define KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR		(1ULL << 62)
-- 
2.23.0