Merge tag 'riscv-for-linus-6.14-mw1' of git://git.kernel.org/pub/scm/…

…linux/kernel/git/riscv/linux Pull RISC-V updates from Palmer Dabbelt: - The PH1520 pinctrl and dwmac drivers are enabeled in defconfig - A redundant AQRL barrier has been removed from the futex cmpxchg implementation - Support for the T-Head vector extensions, which includes exposing these extensions to userspace on systems that implement them - Some more page table information is now printed on die() and systems that cause PA overflows * tag 'riscv-for-linus-6.14-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: riscv: add a warning when physical memory address overflows riscv/mm/fault: add show_pte() before die() riscv: Add ghostwrite vulnerability selftests: riscv: Support xtheadvector in vector tests selftests: riscv: Fix vector tests riscv: hwprobe: Document thead vendor extensions and xtheadvector extension riscv: hwprobe: Add thead vendor extension probing riscv: vector: Support xtheadvector save/restore riscv: Add xtheadvector instruction definitions riscv: csr: Add CSR encodings for CSR_VXRM/CSR_VXSAT RISC-V: define the elements of the VCSR vector CSR riscv: vector: Use vlenb from DT for thead riscv: Add thead and xtheadvector as a vendor extension riscv: dts: allwinner: Add xtheadvector to the D1/D1s devicetree dt-bindings: cpus: add a thead vlen register length property dt-bindings: riscv: Add xtheadvector ISA extension description RISC-V: Mark riscv_v_init() as __init riscv: defconfig: drop RT_GROUP_SCHED=y riscv/futex: Optimize atomic cmpxchg riscv: defconfig: enable pinctrl and dwmac support for TH1520
mariux64 · Jan 31, 2025 · 1b5f3c5 · 1b5f3c5
2 parents fd8c09a + 1019712
commit 1b5f3c5
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diff --git a/Documentation/arch/riscv/hwprobe.rst b/Documentation/arch/riscv/hwprobe.rst
@@ -293,3 +293,13 @@ The following keys are defined:
 
   * :c:macro:`RISCV_HWPROBE_MISALIGNED_VECTOR_UNSUPPORTED`: Misaligned vector accesses are
     not supported at all and will generate a misaligned address fault.
+
+* :c:macro:`RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0`: A bitmask containing the
+  thead vendor extensions that are compatible with the
+  :c:macro:`RISCV_HWPROBE_BASE_BEHAVIOR_IMA`: base system behavior.
+
+  * T-HEAD
+
+    * :c:macro:`RISCV_HWPROBE_VENDOR_EXT_XTHEADVECTOR`: The xtheadvector vendor
+        extension is supported in the T-Head ISA extensions spec starting from
+	commit a18c801634 ("Add T-Head VECTOR vendor extension. ").
diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Documentation/devicetree/bindings/riscv/cpus.yaml
@@ -26,6 +26,18 @@ description: |
 allOf:
   - $ref: /schemas/cpu.yaml#
   - $ref: extensions.yaml
+  - if:
+      not:
+        properties:
+          compatible:
+            contains:
+              enum:
+                - thead,c906
+                - thead,c910
+                - thead,c920
+    then:
+      properties:
+        thead,vlenb: false
 
 properties:
   compatible:
@@ -96,6 +108,13 @@ properties:
     description:
       The blocksize in bytes for the Zicboz cache operations.
 
+  thead,vlenb:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      VLEN/8, the vector register length in bytes. This property is required on
+      thead systems where the vector register length is not identical on all harts, or
+      the vlenb CSR is not available.
+
   # RISC-V has multiple properties for cache op block sizes as the sizes
   # differ between individual CBO extensions
   cache-op-block-size: false

diff --git a/Documentation/devicetree/bindings/riscv/extensions.yaml b/Documentation/devicetree/bindings/riscv/extensions.yaml
@@ -621,13 +621,23 @@ properties:
             latency, as ratified in commit 56ed795 ("Update
             riscv-crypto-spec-vector.adoc") of riscv-crypto.
 
+        # vendor extensions, each extension sorted alphanumerically under the
+        # vendor they belong to. Vendors are sorted alphanumerically as well.
+
+        # Andes
         - const: xandespmu
           description:
             The Andes Technology performance monitor extension for counter overflow
             and privilege mode filtering. For more details, see Counter Related
             Registers in the AX45MP datasheet.
             https://www.andestech.com/wp-content/uploads/AX45MP-1C-Rev.-5.0.0-Datasheet.pdf
 
+        # T-HEAD
+        - const: xtheadvector
+          description:
+            The T-HEAD specific 0.7.1 vector implementation as written in
+            https://github.com/T-head-Semi/thead-extension-spec/blob/95358cb2cca9489361c61d335e03d3134b14133f/xtheadvector.adoc.
+
     allOf:
       # Zcb depends on Zca
       - if:

diff --git a/arch/riscv/Kconfig.errata b/arch/riscv/Kconfig.errata
@@ -119,4 +119,15 @@ config ERRATA_THEAD_PMU
 
 	  If you don't know what to do here, say "Y".
 
+config ERRATA_THEAD_GHOSTWRITE
+	bool "Apply T-Head Ghostwrite errata"
+	depends on ERRATA_THEAD && RISCV_ISA_XTHEADVECTOR
+	default y
+	help
+	  The T-Head C9xx cores have a vulnerability in the xtheadvector
+	  instruction set. When this errata is enabled, the CPUs will be probed
+	  to determine if they are vulnerable and disable xtheadvector.
+
+	  If you don't know what to do here, say "Y".
+
 endmenu # "CPU errata selection"
diff --git a/arch/riscv/Kconfig.vendor b/arch/riscv/Kconfig.vendor
@@ -16,4 +16,30 @@ config RISCV_ISA_VENDOR_EXT_ANDES
 	  If you don't know what to do here, say Y.
 endmenu
 
+menu "T-Head"
+config RISCV_ISA_VENDOR_EXT_THEAD
+	bool "T-Head vendor extension support"
+	select RISCV_ISA_VENDOR_EXT
+	default y
+	help
+	  Say N here to disable detection of and support for all T-Head vendor
+	  extensions. Without this option enabled, T-Head vendor extensions will
+	  not be detected at boot and their presence not reported to userspace.
+
+	  If you don't know what to do here, say Y.
+
+config RISCV_ISA_XTHEADVECTOR
+	bool "xtheadvector extension support"
+	depends on RISCV_ISA_VENDOR_EXT_THEAD
+	depends on RISCV_ISA_V
+	depends on FPU
+	default y
+	help
+	  Say N here if you want to disable all xtheadvector related procedures
+	  in the kernel. This will disable vector for any T-Head board that
+	  contains xtheadvector rather than the standard vector.
+
+	  If you don't know what to do here, say Y.
+endmenu
+
 endmenu
diff --git a/arch/riscv/boot/dts/allwinner/sun20i-d1s.dtsi b/arch/riscv/boot/dts/allwinner/sun20i-d1s.dtsi
@@ -27,7 +27,8 @@
 			riscv,isa = "rv64imafdc";
 			riscv,isa-base = "rv64i";
 			riscv,isa-extensions = "i", "m", "a", "f", "d", "c", "zicntr", "zicsr",
-					       "zifencei", "zihpm";
+					       "zifencei", "zihpm", "xtheadvector";
+			thead,vlenb = <128>;
 			#cooling-cells = <2>;
 
 			cpu0_intc: interrupt-controller {

diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig
@@ -10,7 +10,6 @@ CONFIG_MEMCG=y
 CONFIG_BLK_CGROUP=y
 CONFIG_CGROUP_SCHED=y
 CONFIG_CFS_BANDWIDTH=y
-CONFIG_RT_GROUP_SCHED=y
 CONFIG_CGROUP_PIDS=y
 CONFIG_CGROUP_FREEZER=y
 CONFIG_CGROUP_HUGETLB=y

diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
@@ -10,6 +10,7 @@
 #include <linux/string.h>
 #include <linux/uaccess.h>
 #include <asm/alternative.h>
+#include <asm/bugs.h>
 #include <asm/cacheflush.h>
 #include <asm/cpufeature.h>
 #include <asm/dma-noncoherent.h>
@@ -142,6 +143,31 @@ static bool errata_probe_pmu(unsigned int stage,
 	return true;
 }
 
+static bool errata_probe_ghostwrite(unsigned int stage,
+				    unsigned long arch_id, unsigned long impid)
+{
+	if (!IS_ENABLED(CONFIG_ERRATA_THEAD_GHOSTWRITE))
+		return false;
+
+	/*
+	 * target-c9xx cores report arch_id and impid as 0
+	 *
+	 * While ghostwrite may not affect all c9xx cores that implement
+	 * xtheadvector, there is no futher granularity than c9xx. Assume
+	 * vulnerable for this entire class of processors when xtheadvector is
+	 * enabled.
+	 */
+	if (arch_id != 0 || impid != 0)
+		return false;
+
+	if (stage != RISCV_ALTERNATIVES_EARLY_BOOT)
+		return false;
+
+	ghostwrite_set_vulnerable();
+
+	return true;
+}
+
 static u32 thead_errata_probe(unsigned int stage,
 			      unsigned long archid, unsigned long impid)
 {
@@ -155,6 +181,8 @@ static u32 thead_errata_probe(unsigned int stage,
 	if (errata_probe_pmu(stage, archid, impid))
 		cpu_req_errata |= BIT(ERRATA_THEAD_PMU);
 
+	errata_probe_ghostwrite(stage, archid, impid);
+
 	return cpu_req_errata;
 }
 

diff --git a/arch/riscv/include/asm/bugs.h b/arch/riscv/include/asm/bugs.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Interface for managing mitigations for riscv vulnerabilities.
+ *
+ * Copyright (C) 2024 Rivos Inc.
+ */
+
+#ifndef __ASM_BUGS_H
+#define __ASM_BUGS_H
+
+/* Watch out, ordering is important here. */
+enum mitigation_state {
+	UNAFFECTED,
+	MITIGATED,
+	VULNERABLE,
+};
+
+void ghostwrite_set_vulnerable(void);
+bool ghostwrite_enable_mitigation(void);
+enum mitigation_state ghostwrite_get_state(void);
+
+#endif /* __ASM_BUGS_H */
diff --git a/arch/riscv/include/asm/cpufeature.h b/arch/riscv/include/asm/cpufeature.h
@@ -34,6 +34,8 @@ DECLARE_PER_CPU(struct riscv_cpuinfo, riscv_cpuinfo);
 /* Per-cpu ISA extensions. */
 extern struct riscv_isainfo hart_isa[NR_CPUS];
 
+extern u32 thead_vlenb_of;
+
 void __init riscv_user_isa_enable(void);
 
 #define _RISCV_ISA_EXT_DATA(_name, _id, _subset_exts, _subset_exts_size, _validate) {	\

diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
@@ -30,6 +30,12 @@
 #define SR_VS_CLEAN	_AC(0x00000400, UL)
 #define SR_VS_DIRTY	_AC(0x00000600, UL)
 
+#define SR_VS_THEAD		_AC(0x01800000, UL) /* xtheadvector Status */
+#define SR_VS_OFF_THEAD		_AC(0x00000000, UL)
+#define SR_VS_INITIAL_THEAD	_AC(0x00800000, UL)
+#define SR_VS_CLEAN_THEAD	_AC(0x01000000, UL)
+#define SR_VS_DIRTY_THEAD	_AC(0x01800000, UL)
+
 #define SR_XS		_AC(0x00018000, UL) /* Extension Status */
 #define SR_XS_OFF	_AC(0x00000000, UL)
 #define SR_XS_INITIAL	_AC(0x00008000, UL)
@@ -315,6 +321,15 @@
 #define CSR_STIMECMP		0x14D
 #define CSR_STIMECMPH		0x15D
 
+/* xtheadvector symbolic CSR names */
+#define CSR_VXSAT		0x9
+#define CSR_VXRM		0xa
+
+/* xtheadvector CSR masks */
+#define CSR_VXRM_MASK		3
+#define CSR_VXRM_SHIFT		1
+#define CSR_VXSAT_MASK		1
+
 /* Supervisor-Level Window to Indirectly Accessed Registers (AIA) */
 #define CSR_SISELECT		0x150
 #define CSR_SIREG		0x151

diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h
@@ -25,7 +25,8 @@
 #ifdef CONFIG_ERRATA_THEAD
 #define	ERRATA_THEAD_MAE 0
 #define	ERRATA_THEAD_PMU 1
-#define	ERRATA_THEAD_NUMBER 2
+#define	ERRATA_THEAD_GHOSTWRITE 2
+#define	ERRATA_THEAD_NUMBER 3
 #endif
 
 #ifdef __ASSEMBLY__

diff --git a/arch/riscv/include/asm/futex.h b/arch/riscv/include/asm/futex.h
@@ -85,7 +85,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 
 	__enable_user_access();
 	__asm__ __volatile__ (
-	"1:	lr.w.aqrl %[v],%[u]			\n"
+	"1:	lr.w %[v],%[u]			        \n"
 	"	bne %[v],%z[ov],3f			\n"
 	"2:	sc.w.aqrl %[t],%z[nv],%[u]		\n"
 	"	bnez %[t],1b				\n"

diff --git a/arch/riscv/include/asm/hwprobe.h b/arch/riscv/include/asm/hwprobe.h
@@ -1,14 +1,14 @@
 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
 /*
- * Copyright 2023 Rivos, Inc
+ * Copyright 2023-2024 Rivos, Inc
  */
 
 #ifndef _ASM_HWPROBE_H
 #define _ASM_HWPROBE_H
 
 #include <uapi/asm/hwprobe.h>
 
-#define RISCV_HWPROBE_MAX_KEY 10
+#define RISCV_HWPROBE_MAX_KEY 11
 
 static inline bool riscv_hwprobe_key_is_valid(__s64 key)
 {
@@ -21,6 +21,7 @@ static inline bool hwprobe_key_is_bitmask(__s64 key)
 	case RISCV_HWPROBE_KEY_BASE_BEHAVIOR:
 	case RISCV_HWPROBE_KEY_IMA_EXT_0:
 	case RISCV_HWPROBE_KEY_CPUPERF_0:
+	case RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0:
 		return true;
 	}
 

diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h
@@ -117,7 +117,7 @@ do {							\
 	__set_prev_cpu(__prev->thread);			\
 	if (has_fpu())					\
 		__switch_to_fpu(__prev, __next);	\
-	if (has_vector())					\
+	if (has_vector() || has_xtheadvector())		\
 		__switch_to_vector(__prev, __next);	\
 	if (switch_to_should_flush_icache(__next))	\
 		local_flush_icache_all();		\