[PATCH v7 06/12] arm64/boot: Enable EL2 requirements for SPE_FEAT_FDS

[James Clark]

SPE data source filtering (optional from Armv8.8) requires that traps to
the filter register PMSDSFR be disabled. Document the requirements and
disable the traps if the feature is present.

Tested-by: Leo Yan <leo.yan at arm.com>
Signed-off-by: James Clark <james.clark at linaro.org>
---
 Documentation/arch/arm64/booting.rst | 11 +++++++++++
 arch/arm64/include/asm/el2_setup.h   | 11 +++++++++++
 2 files changed, 22 insertions(+)

diff --git a/Documentation/arch/arm64/booting.rst b/Documentation/arch/arm64/booting.rst
index 2f666a7c303c..e4f953839f71 100644
--- a/Documentation/arch/arm64/booting.rst
+++ b/Documentation/arch/arm64/booting.rst
@@ -466,6 +466,17 @@ Before jumping into the kernel, the following conditions must be met:
     - HDFGWTR2_EL2.nPMICFILTR_EL0 (bit 3) must be initialised to 0b1.
     - HDFGWTR2_EL2.nPMUACR_EL1 (bit 4) must be initialised to 0b1.
 
+  For CPUs with SPE data source filtering (FEAT_SPE_FDS):
+
+  - If EL3 is present:
+
+    - MDCR_EL3.EnPMS3 (bit 42) must be initialised to 0b1.
+
+  - If the kernel is entered at EL1 and EL2 is present:
+
+    - HDFGRTR2_EL2.nPMSDSFR_EL1 (bit 19) must be initialised to 0b1.
+    - HDFGWTR2_EL2.nPMSDSFR_EL1 (bit 19) must be initialised to 0b1.
+
   For CPUs with Memory Copy and Memory Set instructions (FEAT_MOPS):
 
   - If the kernel is entered at EL1 and EL2 is present:
diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h
index 3a4ca7f9acfb..a0361ddcdca4 100644
--- a/arch/arm64/include/asm/el2_setup.h
+++ b/arch/arm64/include/asm/el2_setup.h
@@ -392,6 +392,17 @@
 	orr	x0, x0, #HDFGRTR2_EL2_nPMICFILTR_EL0
 	orr	x0, x0, #HDFGRTR2_EL2_nPMUACR_EL1
 .Lskip_pmuv3p9_\@:
+	/* If SPE is implemented, */
+	__spe_vers_imp .Lskip_spefds_\@, ID_AA64DFR0_EL1_PMSVer_IMP, x1
+	/* we can read PMSIDR and */
+	mrs_s	x1, SYS_PMSIDR_EL1
+	and	x1, x1,  #PMSIDR_EL1_FDS
+	/* if FEAT_SPE_FDS is implemented, */
+	cbz	x1, .Lskip_spefds_\@
+	/* disable traps to PMSDSFR. */
+	orr	x0, x0, #HDFGRTR2_EL2_nPMSDSFR_EL1
+
+.Lskip_spefds_\@:
 	msr_s   SYS_HDFGRTR2_EL2, x0
 	msr_s   SYS_HDFGWTR2_EL2, x0
 	msr_s   SYS_HFGRTR2_EL2, xzr

-- 
2.34.1