[PATCH 3/4] powerpc/pesries: Get STF barrier requirement from H_GET_CPU_CHARACTERISTICS

[Nicholas Piggin]

This allows the hypervisor / firmware to describe this workarounds to
the guest.

Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
---
 arch/powerpc/include/asm/hvcall.h      | 1 +
 arch/powerpc/platforms/pseries/setup.c | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
index f962b339865c..a60ef261f63a 100644
--- a/arch/powerpc/include/asm/hvcall.h
+++ b/arch/powerpc/include/asm/hvcall.h
@@ -395,6 +395,7 @@
 #define H_CPU_BEHAV_FLUSH_LINK_STACK	(1ull << 57) // IBM bit 6
 #define H_CPU_BEHAV_NO_L1D_FLUSH_ENTRY	(1ull << 56) // IBM bit 7
 #define H_CPU_BEHAV_NO_L1D_FLUSH_UACCESS (1ull << 55) // IBM bit 8
+#define H_CPU_BEHAV_NO_STF_BARRIER	(1ull << 54) // IBM bit 9
 
 /* Flag values used in H_REGISTER_PROC_TBL hcall */
 #define PROC_TABLE_OP_MASK	0x18
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 287f33645419..631a0d57b6cd 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -555,6 +555,9 @@ static void init_cpu_char_feature_flags(struct h_cpu_char_result *result)
 	if (result->behaviour & H_CPU_BEHAV_NO_L1D_FLUSH_UACCESS)
 		security_ftr_clear(SEC_FTR_L1D_FLUSH_UACCESS);
 
+	if (result->behaviour & H_CPU_BEHAV_NO_STF_BARRIER)
+		security_ftr_clear(SEC_FTR_STF_BARRIER);
+
 	if (!(result->behaviour & H_CPU_BEHAV_BNDS_CHK_SPEC_BAR))
 		security_ftr_clear(SEC_FTR_BNDS_CHK_SPEC_BAR);
 }
-- 
2.23.0