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* [PATCH v6 0/5] Add support for SBI v0.2
@ 2019-12-18 21:39 Atish Patra
  2019-12-18 21:39 ` [PATCH v6 1/5] RISC-V: Mark existing SBI as 0.1 SBI Atish Patra
                   ` (6 more replies)
  0 siblings, 7 replies; 10+ messages in thread
From: Atish Patra @ 2019-12-18 21:39 UTC (permalink / raw)
  To: linux-kernel
  Cc: Albert Ou, Anup Patel, Atish Patra, Mike Rapoport, Atish Patra,
	Palmer Dabbelt, Paul Walmsley, Palmer Dabbelt, linux-riscv,
	Thomas Gleixner

The Supervisor Binary Interface(SBI) specification[1] now defines a
base extension that provides extendability to add future extensions
while maintaining backward compatibility with previous versions.
The new version is defined as 0.2 and older version is marked as 0.1.


This series adds support v0.2 and a unified calling convention
implementation between 0.1 and 0.2. It also add other SBI v0.2
functionality defined in [2]. The base support for SBI v0.2 is already
available in OpenSBI v0.5. This series needs additional patches[3] in
OpenSBI. 

Tested on both BBL, OpenSBI with/without the above patch series. 

[1] https://github.com/riscv/riscv-sbi-doc/blob/master/riscv-sbi.adoc
[2] https://github.com/riscv/riscv-sbi-doc/pull/27
[3] http://lists.infradead.org/pipermail/opensbi/2019-November/000738.html

Changes from v5->v6
1. Fixed few compilation issues around config.
2. Fixed hart mask generation issues for RFENCE & IPI extensions.

Changes from v4->v5
1. Fixed few minor comments related to static & inline.
2. Make sure that every patch is boot tested individually.

Changes from v3->v4.
1. Rebased on for-next.
2. Fixed issuses with checkpatch --strict.
3. Unfied all IPI/fence related functions.
4. Added Hfence related SBI calls.

Changes from v2->v3.
1. Moved v0.1 extensions to a new config.
2. Added support for relacement extensions of v0.1 extensions.

Changes from v1->v2
1. Removed the legacy calling convention.
2. Moved all SBI related calls to sbi.c.
3. Moved all SBI related macros to uapi.

Atish Patra (5):
RISC-V: Mark existing SBI as 0.1 SBI.
RISC-V: Add basic support for SBI v0.2
RISC-V: Add SBI v0.2 extension definitions
RISC-V: Introduce a new config for SBI v0.1
RISC-V: Implement new SBI v0.2 extensions

arch/riscv/Kconfig           |   6 +
arch/riscv/include/asm/sbi.h | 178 +++++++-----
arch/riscv/kernel/sbi.c      | 522 ++++++++++++++++++++++++++++++++++-
arch/riscv/kernel/setup.c    |   2 +
4 files changed, 635 insertions(+), 73 deletions(-)

--
2.24.0



^ permalink raw reply	[flat|nested] 10+ messages in thread

* [PATCH v6 1/5] RISC-V: Mark existing SBI as 0.1 SBI.
  2019-12-18 21:39 [PATCH v6 0/5] Add support for SBI v0.2 Atish Patra
@ 2019-12-18 21:39 ` Atish Patra
  2019-12-18 21:39 ` [PATCH v6 2/5] RISC-V: Add basic support for SBI v0.2 Atish Patra
                   ` (5 subsequent siblings)
  6 siblings, 0 replies; 10+ messages in thread
From: Atish Patra @ 2019-12-18 21:39 UTC (permalink / raw)
  To: linux-kernel
  Cc: Albert Ou, Atish Patra, Anup Patel, Palmer Dabbelt,
	Mike Rapoport, Atish Patra, Palmer Dabbelt, Paul Walmsley,
	linux-riscv, Thomas Gleixner

As per the new SBI specification, current SBI implementation version
is defined as 0.1 and will be removed/replaced in future. Each of the
function call in 0.1 is defined as a separate extension which makes
easier to replace them one at a time.

Rename existing implementation to reflect that. This patch is just
a preparatory patch for SBI v0.2 and doesn't introduce any functional
changes.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
---
 arch/riscv/include/asm/sbi.h | 44 ++++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 20 deletions(-)

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 2570c1e683d3..b38bc36f7429 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * Copyright (C) 2015 Regents of the University of California
+ * Copyright (c) 2019 Western Digital Corporation or its affiliates.
  */
 
 #ifndef _ASM_RISCV_SBI_H
@@ -9,17 +10,17 @@
 #include <linux/types.h>
 
 #ifdef CONFIG_RISCV_SBI
-#define SBI_SET_TIMER 0
-#define SBI_CONSOLE_PUTCHAR 1
-#define SBI_CONSOLE_GETCHAR 2
-#define SBI_CLEAR_IPI 3
-#define SBI_SEND_IPI 4
-#define SBI_REMOTE_FENCE_I 5
-#define SBI_REMOTE_SFENCE_VMA 6
-#define SBI_REMOTE_SFENCE_VMA_ASID 7
-#define SBI_SHUTDOWN 8
+#define SBI_EXT_0_1_SET_TIMER 0x0
+#define SBI_EXT_0_1_CONSOLE_PUTCHAR 0x1
+#define SBI_EXT_0_1_CONSOLE_GETCHAR 0x2
+#define SBI_EXT_0_1_CLEAR_IPI 0x3
+#define SBI_EXT_0_1_SEND_IPI 0x4
+#define SBI_EXT_0_1_REMOTE_FENCE_I 0x5
+#define SBI_EXT_0_1_REMOTE_SFENCE_VMA 0x6
+#define SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID 0x7
+#define SBI_EXT_0_1_SHUTDOWN 0x8
 
-#define SBI_CALL(which, arg0, arg1, arg2, arg3) ({		\
+#define SBI_CALL(which, arg0, arg1, arg2, arg3) ({             \
 	register uintptr_t a0 asm ("a0") = (uintptr_t)(arg0);	\
 	register uintptr_t a1 asm ("a1") = (uintptr_t)(arg1);	\
 	register uintptr_t a2 asm ("a2") = (uintptr_t)(arg2);	\
@@ -43,48 +44,50 @@
 
 static inline void sbi_console_putchar(int ch)
 {
-	SBI_CALL_1(SBI_CONSOLE_PUTCHAR, ch);
+	SBI_CALL_1(SBI_EXT_0_1_CONSOLE_PUTCHAR, ch);
 }
 
 static inline int sbi_console_getchar(void)
 {
-	return SBI_CALL_0(SBI_CONSOLE_GETCHAR);
+	return SBI_CALL_0(SBI_EXT_0_1_CONSOLE_GETCHAR);
 }
 
 static inline void sbi_set_timer(uint64_t stime_value)
 {
 #if __riscv_xlen == 32
-	SBI_CALL_2(SBI_SET_TIMER, stime_value, stime_value >> 32);
+	SBI_CALL_2(SBI_EXT_0_1_SET_TIMER, stime_value,
+			  stime_value >> 32);
 #else
-	SBI_CALL_1(SBI_SET_TIMER, stime_value);
+	SBI_CALL_1(SBI_EXT_0_1_SET_TIMER, stime_value);
 #endif
 }
 
 static inline void sbi_shutdown(void)
 {
-	SBI_CALL_0(SBI_SHUTDOWN);
+	SBI_CALL_0(SBI_EXT_0_1_SHUTDOWN);
 }
 
 static inline void sbi_clear_ipi(void)
 {
-	SBI_CALL_0(SBI_CLEAR_IPI);
+	SBI_CALL_0(SBI_EXT_0_1_CLEAR_IPI);
 }
 
 static inline void sbi_send_ipi(const unsigned long *hart_mask)
 {
-	SBI_CALL_1(SBI_SEND_IPI, hart_mask);
+	SBI_CALL_1(SBI_EXT_0_1_SEND_IPI, hart_mask);
 }
 
 static inline void sbi_remote_fence_i(const unsigned long *hart_mask)
 {
-	SBI_CALL_1(SBI_REMOTE_FENCE_I, hart_mask);
+	SBI_CALL_1(SBI_EXT_0_1_REMOTE_FENCE_I, hart_mask);
 }
 
 static inline void sbi_remote_sfence_vma(const unsigned long *hart_mask,
 					 unsigned long start,
 					 unsigned long size)
 {
-	SBI_CALL_3(SBI_REMOTE_SFENCE_VMA, hart_mask, start, size);
+	SBI_CALL_3(SBI_EXT_0_1_REMOTE_SFENCE_VMA, hart_mask,
+			  start, size);
 }
 
 static inline void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
@@ -92,7 +95,8 @@ static inline void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
 					      unsigned long size,
 					      unsigned long asid)
 {
-	SBI_CALL_4(SBI_REMOTE_SFENCE_VMA_ASID, hart_mask, start, size, asid);
+	SBI_CALL_4(SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID, hart_mask,
+			  start, size, asid);
 }
 #else /* CONFIG_RISCV_SBI */
 /* stubs for code that is only reachable under IS_ENABLED(CONFIG_RISCV_SBI): */
-- 
2.24.0



^ permalink raw reply	[flat|nested] 10+ messages in thread

* [PATCH v6 2/5] RISC-V: Add basic support for SBI v0.2
  2019-12-18 21:39 [PATCH v6 0/5] Add support for SBI v0.2 Atish Patra
  2019-12-18 21:39 ` [PATCH v6 1/5] RISC-V: Mark existing SBI as 0.1 SBI Atish Patra
@ 2019-12-18 21:39 ` Atish Patra
  2019-12-18 21:39 ` [PATCH v6 3/5] RISC-V: Add SBI v0.2 extension definitions Atish Patra
                   ` (4 subsequent siblings)
  6 siblings, 0 replies; 10+ messages in thread
From: Atish Patra @ 2019-12-18 21:39 UTC (permalink / raw)
  To: linux-kernel
  Cc: Albert Ou, Atish Patra, Anup Patel, Palmer Dabbelt,
	Mike Rapoport, Atish Patra, Palmer Dabbelt, Paul Walmsley,
	linux-riscv, Thomas Gleixner

The SBI v0.2 introduces a base extension which is backward compatible
with v0.1. Implement all helper functions and minimum required SBI
calls from v0.2 for now. All other base extension function will be
added later as per need.
As v0.2 calling convention is backward compatible with v0.1, remove
the v0.1 helper functions and just use v0.2 calling convention.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
---
 arch/riscv/include/asm/sbi.h | 139 ++++++++++----------
 arch/riscv/kernel/sbi.c      | 243 ++++++++++++++++++++++++++++++++++-
 arch/riscv/kernel/setup.c    |   2 +
 3 files changed, 310 insertions(+), 74 deletions(-)

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index b38bc36f7429..1aeb4bb7baa8 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -10,93 +10,88 @@
 #include <linux/types.h>
 
 #ifdef CONFIG_RISCV_SBI
-#define SBI_EXT_0_1_SET_TIMER 0x0
-#define SBI_EXT_0_1_CONSOLE_PUTCHAR 0x1
-#define SBI_EXT_0_1_CONSOLE_GETCHAR 0x2
-#define SBI_EXT_0_1_CLEAR_IPI 0x3
-#define SBI_EXT_0_1_SEND_IPI 0x4
-#define SBI_EXT_0_1_REMOTE_FENCE_I 0x5
-#define SBI_EXT_0_1_REMOTE_SFENCE_VMA 0x6
-#define SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID 0x7
-#define SBI_EXT_0_1_SHUTDOWN 0x8
+enum sbi_ext_id {
+	SBI_EXT_0_1_SET_TIMER = 0x0,
+	SBI_EXT_0_1_CONSOLE_PUTCHAR = 0x1,
+	SBI_EXT_0_1_CONSOLE_GETCHAR = 0x2,
+	SBI_EXT_0_1_CLEAR_IPI = 0x3,
+	SBI_EXT_0_1_SEND_IPI = 0x4,
+	SBI_EXT_0_1_REMOTE_FENCE_I = 0x5,
+	SBI_EXT_0_1_REMOTE_SFENCE_VMA = 0x6,
+	SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID = 0x7,
+	SBI_EXT_0_1_SHUTDOWN = 0x8,
+	SBI_EXT_BASE = 0x10,
+};
 
-#define SBI_CALL(which, arg0, arg1, arg2, arg3) ({             \
-	register uintptr_t a0 asm ("a0") = (uintptr_t)(arg0);	\
-	register uintptr_t a1 asm ("a1") = (uintptr_t)(arg1);	\
-	register uintptr_t a2 asm ("a2") = (uintptr_t)(arg2);	\
-	register uintptr_t a3 asm ("a3") = (uintptr_t)(arg3);	\
-	register uintptr_t a7 asm ("a7") = (uintptr_t)(which);	\
-	asm volatile ("ecall"					\
-		      : "+r" (a0)				\
-		      : "r" (a1), "r" (a2), "r" (a3), "r" (a7)	\
-		      : "memory");				\
-	a0;							\
-})
+enum sbi_ext_base_fid {
+	SBI_EXT_BASE_GET_SPEC_VERSION = 0,
+	SBI_EXT_BASE_GET_IMP_ID,
+	SBI_EXT_BASE_GET_IMP_VERSION,
+	SBI_EXT_BASE_PROBE_EXT,
+	SBI_EXT_BASE_GET_MVENDORID,
+	SBI_EXT_BASE_GET_MARCHID,
+	SBI_EXT_BASE_GET_MIMPID,
+};
 
-/* Lazy implementations until SBI is finalized */
-#define SBI_CALL_0(which) SBI_CALL(which, 0, 0, 0, 0)
-#define SBI_CALL_1(which, arg0) SBI_CALL(which, arg0, 0, 0, 0)
-#define SBI_CALL_2(which, arg0, arg1) SBI_CALL(which, arg0, arg1, 0, 0)
-#define SBI_CALL_3(which, arg0, arg1, arg2) \
-		SBI_CALL(which, arg0, arg1, arg2, 0)
-#define SBI_CALL_4(which, arg0, arg1, arg2, arg3) \
-		SBI_CALL(which, arg0, arg1, arg2, arg3)
+#define SBI_SPEC_VERSION_DEFAULT	0x1
+#define SBI_SPEC_VERSION_MAJOR_SHIFT	24
+#define SBI_SPEC_VERSION_MAJOR_MASK	0x7f
+#define SBI_SPEC_VERSION_MINOR_MASK	0xffffff
 
-static inline void sbi_console_putchar(int ch)
-{
-	SBI_CALL_1(SBI_EXT_0_1_CONSOLE_PUTCHAR, ch);
-}
+/* SBI return error codes */
+#define SBI_SUCCESS		0
+#define SBI_ERR_FAILURE		-1
+#define SBI_ERR_NOT_SUPPORTED	-2
+#define SBI_ERR_INVALID_PARAM   -3
+#define SBI_ERR_DENIED		-4
+#define SBI_ERR_INVALID_ADDRESS -5
 
-static inline int sbi_console_getchar(void)
-{
-	return SBI_CALL_0(SBI_EXT_0_1_CONSOLE_GETCHAR);
-}
+extern unsigned long sbi_spec_version;
+struct sbiret {
+	long error;
+	long value;
+};
 
-static inline void sbi_set_timer(uint64_t stime_value)
-{
-#if __riscv_xlen == 32
-	SBI_CALL_2(SBI_EXT_0_1_SET_TIMER, stime_value,
-			  stime_value >> 32);
-#else
-	SBI_CALL_1(SBI_EXT_0_1_SET_TIMER, stime_value);
-#endif
-}
-
-static inline void sbi_shutdown(void)
-{
-	SBI_CALL_0(SBI_EXT_0_1_SHUTDOWN);
-}
+int sbi_init(void);
+struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
+			unsigned long arg1, unsigned long arg2,
+			unsigned long arg3, unsigned long arg4,
+			unsigned long arg5);
 
-static inline void sbi_clear_ipi(void)
-{
-	SBI_CALL_0(SBI_EXT_0_1_CLEAR_IPI);
-}
+void sbi_console_putchar(int ch);
+int sbi_console_getchar(void);
+void sbi_set_timer(uint64_t stime_value);
+void sbi_shutdown(void);
+void sbi_clear_ipi(void);
+void sbi_send_ipi(const unsigned long *hart_mask);
+void sbi_remote_fence_i(const unsigned long *hart_mask);
+void sbi_remote_sfence_vma(const unsigned long *hart_mask,
+			   unsigned long start,
+			   unsigned long size);
 
-static inline void sbi_send_ipi(const unsigned long *hart_mask)
-{
-	SBI_CALL_1(SBI_EXT_0_1_SEND_IPI, hart_mask);
-}
+void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
+				unsigned long start,
+				unsigned long size,
+				unsigned long asid);
+int sbi_probe_extension(int ext);
 
-static inline void sbi_remote_fence_i(const unsigned long *hart_mask)
+/* Check if current SBI specification version is 0.1 or not */
+static inline int sbi_spec_is_0_1(void)
 {
-	SBI_CALL_1(SBI_EXT_0_1_REMOTE_FENCE_I, hart_mask);
+	return (sbi_spec_version == SBI_SPEC_VERSION_DEFAULT) ? 1 : 0;
 }
 
-static inline void sbi_remote_sfence_vma(const unsigned long *hart_mask,
-					 unsigned long start,
-					 unsigned long size)
+/* Get the major version of SBI */
+static inline unsigned long sbi_major_version(void)
 {
-	SBI_CALL_3(SBI_EXT_0_1_REMOTE_SFENCE_VMA, hart_mask,
-			  start, size);
+	return (sbi_spec_version >> SBI_SPEC_VERSION_MAJOR_SHIFT) &
+		SBI_SPEC_VERSION_MAJOR_MASK;
 }
 
-static inline void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
-					      unsigned long start,
-					      unsigned long size,
-					      unsigned long asid)
+/* Get the minor version of SBI */
+static inline unsigned long sbi_minor_version(void)
 {
-	SBI_CALL_4(SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID, hart_mask,
-			  start, size, asid);
+	return sbi_spec_version & SBI_SPEC_VERSION_MINOR_MASK;
 }
 #else /* CONFIG_RISCV_SBI */
 /* stubs for code that is only reachable under IS_ENABLED(CONFIG_RISCV_SBI): */
diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
index f6c7c3e82d28..33632e7f91da 100644
--- a/arch/riscv/kernel/sbi.c
+++ b/arch/riscv/kernel/sbi.c
@@ -1,17 +1,256 @@
 // SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SBI initialilization and all extension implementation.
+ *
+ * Copyright (c) 2019 Western Digital Corporation or its affiliates.
+ */
 
 #include <linux/init.h>
 #include <linux/pm.h>
 #include <asm/sbi.h>
 
+/* default SBI version is 0.1 */
+unsigned long sbi_spec_version = SBI_SPEC_VERSION_DEFAULT;
+EXPORT_SYMBOL(sbi_spec_version);
+
+struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
+			unsigned long arg1, unsigned long arg2,
+			unsigned long arg3, unsigned long arg4,
+			unsigned long arg5)
+{
+	struct sbiret ret;
+
+	register uintptr_t a0 asm ("a0") = (uintptr_t)(arg0);
+	register uintptr_t a1 asm ("a1") = (uintptr_t)(arg1);
+	register uintptr_t a2 asm ("a2") = (uintptr_t)(arg2);
+	register uintptr_t a3 asm ("a3") = (uintptr_t)(arg3);
+	register uintptr_t a4 asm ("a4") = (uintptr_t)(arg4);
+	register uintptr_t a5 asm ("a5") = (uintptr_t)(arg5);
+	register uintptr_t a6 asm ("a6") = (uintptr_t)(fid);
+	register uintptr_t a7 asm ("a7") = (uintptr_t)(ext);
+	asm volatile ("ecall"
+		      : "+r" (a0), "+r" (a1)
+		      : "r" (a2), "r" (a3), "r" (a4), "r" (a5), "r" (a6), "r" (a7)
+		      : "memory");
+	ret.error = a0;
+	ret.value = a1;
+
+	return ret;
+}
+EXPORT_SYMBOL(sbi_ecall);
+
+static int sbi_err_map_linux_errno(int err)
+{
+	switch (err) {
+	case SBI_SUCCESS:
+		return 0;
+	case SBI_ERR_DENIED:
+		return -EPERM;
+	case SBI_ERR_INVALID_PARAM:
+		return -EINVAL;
+	case SBI_ERR_INVALID_ADDRESS:
+		return -EFAULT;
+	case SBI_ERR_NOT_SUPPORTED:
+	case SBI_ERR_FAILURE:
+	default:
+		return -ENOTSUPP;
+	};
+}
+
+/**
+ * sbi_console_putchar() - Writes given character to the console device.
+ * @ch: The data to be written to the console.
+ *
+ * Return: None
+ */
+void sbi_console_putchar(int ch)
+{
+	sbi_ecall(SBI_EXT_0_1_CONSOLE_PUTCHAR, 0, ch, 0, 0, 0, 0, 0);
+}
+EXPORT_SYMBOL(sbi_console_putchar);
+
+/**
+ * sbi_console_getchar() - Reads a byte from console device.
+ *
+ * Returns the value read from console.
+ */
+int sbi_console_getchar(void)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_0_1_CONSOLE_GETCHAR, 0, 0, 0, 0, 0, 0, 0);
+
+	return ret.error;
+}
+EXPORT_SYMBOL(sbi_console_getchar);
+
+/**
+ * sbi_set_timer() - Program the timer for next timer event.
+ * @stime_value: The value after which next timer event should fire.
+ *
+ * Return: None
+ */
+void sbi_set_timer(uint64_t stime_value)
+{
+#if __riscv_xlen == 32
+	sbi_ecall(SBI_EXT_0_1_SET_TIMER, 0, stime_value,
+			  stime_value >> 32, 0, 0, 0, 0);
+#else
+	sbi_ecall(SBI_EXT_0_1_SET_TIMER, 0, stime_value, 0, 0, 0, 0, 0);
+#endif
+}
+EXPORT_SYMBOL(sbi_set_timer);
+
+/**
+ * sbi_shutdown() - Remove all the harts from executing supervisor code.
+ *
+ * Return: None
+ */
+void sbi_shutdown(void)
+{
+	sbi_ecall(SBI_EXT_0_1_SHUTDOWN, 0, 0, 0, 0, 0, 0, 0);
+}
+EXPORT_SYMBOL(sbi_shutdown);
+
+/**
+ * sbi_clear_ipi() - Clear any pending IPIs for the calling hart.
+ *
+ * Return: None
+ */
+void sbi_clear_ipi(void)
+{
+	sbi_ecall(SBI_EXT_0_1_CLEAR_IPI, 0, 0, 0, 0, 0, 0, 0);
+}
+
+/**
+ * sbi_send_ipi() - Send an IPI to any hart.
+ * @hart_mask: A cpu mask containing all the target harts.
+ *
+ * Return: None
+ */
+void sbi_send_ipi(const unsigned long *hart_mask)
+{
+	sbi_ecall(SBI_EXT_0_1_SEND_IPI, 0, (unsigned long)hart_mask,
+			0, 0, 0, 0, 0);
+}
+EXPORT_SYMBOL(sbi_send_ipi);
+
+/**
+ * sbi_remote_fence_i() - Execute FENCE.I instruction on given remote harts.
+ * @hart_mask: A cpu mask containing all the target harts.
+ *
+ * Return: None
+ */
+void sbi_remote_fence_i(const unsigned long *hart_mask)
+{
+	sbi_ecall(SBI_EXT_0_1_REMOTE_FENCE_I, 0, (unsigned long)hart_mask,
+			0, 0, 0, 0, 0);
+}
+EXPORT_SYMBOL(sbi_remote_fence_i);
+
+/**
+ * sbi_remote_sfence_vma() - Execute SFENCE.VMA instructions on given remote
+ *			     harts for the specified virtual address range.
+ * @hart_mask: A cpu mask containing all the target harts.
+ * @start: Start of the virtual address
+ * @size: Total size of the virtual address range.
+ *
+ * Return: None
+ */
+void sbi_remote_sfence_vma(const unsigned long *hart_mask,
+					 unsigned long start,
+					 unsigned long size)
+{
+	sbi_ecall(SBI_EXT_0_1_REMOTE_SFENCE_VMA, 0,
+			(unsigned long)hart_mask, start, size, 0, 0, 0);
+}
+EXPORT_SYMBOL(sbi_remote_sfence_vma);
+
+/**
+ * sbi_remote_sfence_vma_asid() - Execute SFENCE.VMA instructions on given
+ * remote harts for a virtual address range belonging to a specific ASID.
+ *
+ * @hart_mask: A cpu mask containing all the target harts.
+ * @start: Start of the virtual address
+ * @size: Total size of the virtual address range.
+ * @asid: The value of address space identifier (ASID).
+ *
+ * Return: None
+ */
+void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
+					      unsigned long start,
+					      unsigned long size,
+					      unsigned long asid)
+{
+	sbi_ecall(SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID, 0,
+			(unsigned long)hart_mask, start, size, asid, 0, 0);
+}
+EXPORT_SYMBOL(sbi_remote_sfence_vma_asid);
+
+/**
+ * sbi_probe_extension() - Check if an SBI extension ID is supported or not.
+ * @extid: The extension ID to be probed.
+ *
+ * Return: Extension specific nonzero value f yes, -ENOTSUPP otherwise.
+ */
+int sbi_probe_extension(int extid)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_BASE, SBI_EXT_BASE_PROBE_EXT, extid,
+			0, 0, 0, 0, 0);
+	if (!ret.error)
+		if (ret.value)
+			return ret.value;
+
+	return -ENOTSUPP;
+}
+EXPORT_SYMBOL(sbi_probe_extension);
+
+static long __sbi_base_ecall(int fid)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_BASE, fid, 0, 0, 0, 0, 0, 0);
+	if (!ret.error)
+		return ret.value;
+	else
+		return sbi_err_map_linux_errno(ret.error);
+}
+
+static inline long sbi_get_spec_version(void)
+{
+	return __sbi_base_ecall(SBI_EXT_BASE_GET_SPEC_VERSION);
+}
+
+static inline long sbi_get_firmware_id(void)
+{
+	return __sbi_base_ecall(SBI_EXT_BASE_GET_IMP_ID);
+}
+
+static inline long sbi_get_firmware_version(void)
+{
+	return __sbi_base_ecall(SBI_EXT_BASE_GET_IMP_VERSION);
+}
+
 static void sbi_power_off(void)
 {
 	sbi_shutdown();
 }
 
-static int __init sbi_init(void)
+int __init sbi_init(void)
 {
+	int ret;
+
 	pm_power_off = sbi_power_off;
+	ret = sbi_get_spec_version();
+	if (ret > 0)
+		sbi_spec_version = ret;
+
+	pr_info("SBI specification v%lu.%lu detected\n",
+		sbi_major_version(), sbi_minor_version());
+	if (!sbi_spec_is_0_1())
+		pr_info("SBI implementation ID=0x%lx Version=0x%lx\n",
+			sbi_get_firmware_id(), sbi_get_firmware_version());
 	return 0;
 }
-early_initcall(sbi_init);
diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 365ff8420bfe..f0a3c51e3d1b 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -22,6 +22,7 @@
 #include <asm/sections.h>
 #include <asm/pgtable.h>
 #include <asm/smp.h>
+#include <asm/sbi.h>
 #include <asm/tlbflush.h>
 #include <asm/thread_info.h>
 
@@ -74,6 +75,7 @@ void __init setup_arch(char **cmdline_p)
 	swiotlb_init(1);
 #endif
 
+	sbi_init();
 #ifdef CONFIG_SMP
 	setup_smp();
 #endif
-- 
2.24.0



^ permalink raw reply	[flat|nested] 10+ messages in thread

* [PATCH v6 3/5] RISC-V: Add SBI v0.2 extension definitions
  2019-12-18 21:39 [PATCH v6 0/5] Add support for SBI v0.2 Atish Patra
  2019-12-18 21:39 ` [PATCH v6 1/5] RISC-V: Mark existing SBI as 0.1 SBI Atish Patra
  2019-12-18 21:39 ` [PATCH v6 2/5] RISC-V: Add basic support for SBI v0.2 Atish Patra
@ 2019-12-18 21:39 ` Atish Patra
  2019-12-19  6:55   ` Anup Patel
  2019-12-18 21:39 ` [PATCH v6 4/5] RISC-V: Introduce a new config for SBI v0.1 Atish Patra
                   ` (3 subsequent siblings)
  6 siblings, 1 reply; 10+ messages in thread
From: Atish Patra @ 2019-12-18 21:39 UTC (permalink / raw)
  To: linux-kernel
  Cc: Albert Ou, Anup Patel, Atish Patra, Mike Rapoport, Atish Patra,
	Palmer Dabbelt, Paul Walmsley, Palmer Dabbelt, linux-riscv,
	Thomas Gleixner

Few v0.1 SBI calls are being replaced by new SBI calls that follows
v0.2 calling convention.

This patch just defines these new extensions.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 arch/riscv/include/asm/sbi.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 1aeb4bb7baa8..9612133213ba 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -21,6 +21,9 @@ enum sbi_ext_id {
 	SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID = 0x7,
 	SBI_EXT_0_1_SHUTDOWN = 0x8,
 	SBI_EXT_BASE = 0x10,
+	SBI_EXT_TIME = 0x54494D45,
+	SBI_EXT_IPI = 0x735049,
+	SBI_EXT_RFENCE = 0x52464E43,
 };
 
 enum sbi_ext_base_fid {
@@ -33,6 +36,24 @@ enum sbi_ext_base_fid {
 	SBI_EXT_BASE_GET_MIMPID,
 };
 
+enum sbi_ext_time_fid {
+	SBI_EXT_TIME_SET_TIMER = 0,
+};
+
+enum sbi_ext_ipi_fid {
+	SBI_EXT_IPI_SEND_IPI = 0,
+};
+
+enum sbi_ext_rfence_fid {
+	SBI_EXT_RFENCE_REMOTE_FENCE_I = 0,
+	SBI_EXT_RFENCE_REMOTE_SFENCE_VMA,
+	SBI_EXT_RFENCE_REMOTE_SFENCE_VMA_ASID,
+	SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA,
+	SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA_VMID,
+	SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA,
+	SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA_ASID,
+};
+
 #define SBI_SPEC_VERSION_DEFAULT	0x1
 #define SBI_SPEC_VERSION_MAJOR_SHIFT	24
 #define SBI_SPEC_VERSION_MAJOR_MASK	0x7f
-- 
2.24.0



^ permalink raw reply	[flat|nested] 10+ messages in thread

* [PATCH v6 4/5] RISC-V: Introduce a new config for SBI v0.1
  2019-12-18 21:39 [PATCH v6 0/5] Add support for SBI v0.2 Atish Patra
                   ` (2 preceding siblings ...)
  2019-12-18 21:39 ` [PATCH v6 3/5] RISC-V: Add SBI v0.2 extension definitions Atish Patra
@ 2019-12-18 21:39 ` Atish Patra
  2019-12-18 21:39 ` [PATCH v6 5/5] RISC-V: Implement new SBI v0.2 extensions Atish Patra
                   ` (2 subsequent siblings)
  6 siblings, 0 replies; 10+ messages in thread
From: Atish Patra @ 2019-12-18 21:39 UTC (permalink / raw)
  To: linux-kernel
  Cc: Albert Ou, Anup Patel, Atish Patra, Mike Rapoport, Atish Patra,
	Palmer Dabbelt, Paul Walmsley, Palmer Dabbelt, linux-riscv,
	Thomas Gleixner

We now have SBI v0.2 which is more scalable and extendable to handle
future needs for RISC-V supervisor interfaces.

Introduce a new config and move all SBI v0.1 code under that config.
This allows to implement the new replacement SBI extensions cleanly
and remove v0.1 extensions easily in future. Currently, the config
is enabled by default. Once all M-mode software, with v0.1, is no
longer in use, this config option and all relevant code can be easily
removed.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
---
 arch/riscv/Kconfig           |   6 ++
 arch/riscv/include/asm/sbi.h |   2 +
 arch/riscv/kernel/sbi.c      | 137 +++++++++++++++++++++++++++++------
 3 files changed, 121 insertions(+), 24 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 759ffb00267c..14b6726bef50 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -305,6 +305,12 @@ config SECCOMP
 	  and the task is only allowed to execute a few safe syscalls
 	  defined by each seccomp mode.
 
+config RISCV_SBI_V01
+	bool "SBI v0.1 support"
+	default y
+	help
+	  This config allows kernel to use SBI v0.1 APIs. This will be
+	  deprecated in future once legacy M-mode software are no longer in use.
 endmenu
 
 menu "Boot options"
diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 9612133213ba..89a25a049d12 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -11,6 +11,7 @@
 
 #ifdef CONFIG_RISCV_SBI
 enum sbi_ext_id {
+#ifdef CONFIG_RISCV_SBI_V01
 	SBI_EXT_0_1_SET_TIMER = 0x0,
 	SBI_EXT_0_1_CONSOLE_PUTCHAR = 0x1,
 	SBI_EXT_0_1_CONSOLE_GETCHAR = 0x2,
@@ -20,6 +21,7 @@ enum sbi_ext_id {
 	SBI_EXT_0_1_REMOTE_SFENCE_VMA = 0x6,
 	SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID = 0x7,
 	SBI_EXT_0_1_SHUTDOWN = 0x8,
+#endif
 	SBI_EXT_BASE = 0x10,
 	SBI_EXT_TIME = 0x54494D45,
 	SBI_EXT_IPI = 0x735049,
diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
index 33632e7f91da..265637cb5eb0 100644
--- a/arch/riscv/kernel/sbi.c
+++ b/arch/riscv/kernel/sbi.c
@@ -13,6 +13,13 @@
 unsigned long sbi_spec_version = SBI_SPEC_VERSION_DEFAULT;
 EXPORT_SYMBOL(sbi_spec_version);
 
+static void (*__sbi_set_timer)(uint64_t stime);
+static int (*__sbi_send_ipi)(const unsigned long *hart_mask);
+static int (*__sbi_rfence)(int fid, const unsigned long *hart_mask,
+			   unsigned long hbase, unsigned long start,
+			   unsigned long size, unsigned long arg4,
+			   unsigned long arg5);
+
 struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
 			unsigned long arg1, unsigned long arg2,
 			unsigned long arg3, unsigned long arg4,
@@ -57,6 +64,7 @@ static int sbi_err_map_linux_errno(int err)
 	};
 }
 
+#ifdef CONFIG_RISCV_SBI_V01
 /**
  * sbi_console_putchar() - Writes given character to the console device.
  * @ch: The data to be written to the console.
@@ -85,41 +93,115 @@ int sbi_console_getchar(void)
 EXPORT_SYMBOL(sbi_console_getchar);
 
 /**
- * sbi_set_timer() - Program the timer for next timer event.
- * @stime_value: The value after which next timer event should fire.
+ * sbi_shutdown() - Remove all the harts from executing supervisor code.
  *
  * Return: None
  */
-void sbi_set_timer(uint64_t stime_value)
+void sbi_shutdown(void)
 {
-#if __riscv_xlen == 32
-	sbi_ecall(SBI_EXT_0_1_SET_TIMER, 0, stime_value,
-			  stime_value >> 32, 0, 0, 0, 0);
-#else
-	sbi_ecall(SBI_EXT_0_1_SET_TIMER, 0, stime_value, 0, 0, 0, 0, 0);
-#endif
+	sbi_ecall(SBI_EXT_0_1_SHUTDOWN, 0, 0, 0, 0, 0, 0, 0);
 }
 EXPORT_SYMBOL(sbi_set_timer);
 
 /**
- * sbi_shutdown() - Remove all the harts from executing supervisor code.
+ * sbi_clear_ipi() - Clear any pending IPIs for the calling hart.
  *
  * Return: None
  */
-void sbi_shutdown(void)
+void sbi_clear_ipi(void)
 {
-	sbi_ecall(SBI_EXT_0_1_SHUTDOWN, 0, 0, 0, 0, 0, 0, 0);
+	sbi_ecall(SBI_EXT_0_1_CLEAR_IPI, 0, 0, 0, 0, 0, 0, 0);
 }
 EXPORT_SYMBOL(sbi_shutdown);
 
 /**
- * sbi_clear_ipi() - Clear any pending IPIs for the calling hart.
+ * sbi_set_timer_v01() - Program the timer for next timer event.
+ * @stime_value: The value after which next timer event should fire.
  *
  * Return: None
  */
-void sbi_clear_ipi(void)
+static void __sbi_set_timer_v01(uint64_t stime_value)
 {
-	sbi_ecall(SBI_EXT_0_1_CLEAR_IPI, 0, 0, 0, 0, 0, 0, 0);
+#if __riscv_xlen == 32
+	sbi_ecall(SBI_EXT_0_1_SET_TIMER, 0, stime_value,
+		  stime_value >> 32, 0, 0, 0, 0);
+#else
+	sbi_ecall(SBI_EXT_0_1_SET_TIMER, 0, stime_value, 0, 0, 0, 0, 0);
+#endif
+}
+
+static int __sbi_send_ipi_v01(const unsigned long *hart_mask)
+{
+	sbi_ecall(SBI_EXT_0_1_SEND_IPI, 0, (unsigned long)hart_mask,
+		  0, 0, 0, 0, 0);
+	return 0;
+}
+
+static int __sbi_rfence_v01(int fid, const unsigned long *hart_mask,
+			    unsigned long hbase, unsigned long start,
+			    unsigned long size, unsigned long arg4,
+			    unsigned long arg5)
+{
+	int result = 0;
+
+	/* v0.2 function IDs are equivalent to v0.1 extension IDs */
+	switch (fid) {
+	case SBI_EXT_RFENCE_REMOTE_FENCE_I:
+		sbi_ecall(SBI_EXT_0_1_REMOTE_FENCE_I, 0,
+			  (unsigned long)hart_mask, 0, 0, 0, 0, 0);
+		break;
+	case SBI_EXT_RFENCE_REMOTE_SFENCE_VMA:
+		sbi_ecall(SBI_EXT_0_1_REMOTE_SFENCE_VMA, 0,
+			  (unsigned long)hart_mask, start, size,
+			  0, 0, 0);
+		break;
+	case SBI_EXT_RFENCE_REMOTE_SFENCE_VMA_ASID:
+		sbi_ecall(SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID, 0,
+			  (unsigned long)hart_mask, start, size,
+			  arg4, 0, 0);
+		break;
+	default:
+		pr_err("SBI call [%d]not supported in SBI v0.1\n", fid);
+		result = -EINVAL;
+	}
+
+	return result;
+}
+#else
+static void __sbi_set_timer_v01(uint64_t stime_value)
+{
+	pr_warn("Timer extension is not available in SBI v%lu.%lu\n",
+		sbi_major_version(), sbi_minor_version());
+}
+static int __sbi_send_ipi_v01(const unsigned long *hart_mask)
+{
+	pr_warn("IPI extension is not available in SBI v%lu.%lu\n",
+		sbi_major_version(), sbi_minor_version());
+
+	return 0;
+}
+static int __sbi_rfence_v01(int fid,
+			    const unsigned long *hart_mask,
+			    unsigned long hbase, unsigned long start,
+			    unsigned long size, unsigned long arg4,
+			    unsigned long arg5)
+{
+	pr_warn("remote fence extension is not available in SBI v%lu.%lu\n",
+		sbi_major_version(), sbi_minor_version());
+
+	return 0;
+}
+#endif /* CONFIG_RISCV_SBI_V01 */
+
+/**
+ * sbi_set_timer() - Program the timer for next timer event.
+ * @stime_value: The value after which next timer event should fire.
+ *
+ * Return: None
+ */
+void sbi_set_timer(uint64_t stime_value)
+{
+	__sbi_set_timer(stime_value);
 }
 
 /**
@@ -130,11 +212,11 @@ void sbi_clear_ipi(void)
  */
 void sbi_send_ipi(const unsigned long *hart_mask)
 {
-	sbi_ecall(SBI_EXT_0_1_SEND_IPI, 0, (unsigned long)hart_mask,
-			0, 0, 0, 0, 0);
+	__sbi_send_ipi(hart_mask);
 }
 EXPORT_SYMBOL(sbi_send_ipi);
 
+
 /**
  * sbi_remote_fence_i() - Execute FENCE.I instruction on given remote harts.
  * @hart_mask: A cpu mask containing all the target harts.
@@ -143,8 +225,8 @@ EXPORT_SYMBOL(sbi_send_ipi);
  */
 void sbi_remote_fence_i(const unsigned long *hart_mask)
 {
-	sbi_ecall(SBI_EXT_0_1_REMOTE_FENCE_I, 0, (unsigned long)hart_mask,
-			0, 0, 0, 0, 0);
+	__sbi_rfence(SBI_EXT_RFENCE_REMOTE_FENCE_I,
+		     hart_mask, 0, 0, 0, 0, 0);
 }
 EXPORT_SYMBOL(sbi_remote_fence_i);
 
@@ -161,8 +243,8 @@ void sbi_remote_sfence_vma(const unsigned long *hart_mask,
 					 unsigned long start,
 					 unsigned long size)
 {
-	sbi_ecall(SBI_EXT_0_1_REMOTE_SFENCE_VMA, 0,
-			(unsigned long)hart_mask, start, size, 0, 0, 0);
+	__sbi_rfence(SBI_EXT_RFENCE_REMOTE_SFENCE_VMA,
+		     hart_mask, 0, start, size, 0, 0);
 }
 EXPORT_SYMBOL(sbi_remote_sfence_vma);
 
@@ -182,8 +264,8 @@ void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
 					      unsigned long size,
 					      unsigned long asid)
 {
-	sbi_ecall(SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID, 0,
-			(unsigned long)hart_mask, start, size, asid, 0, 0);
+	__sbi_rfence(SBI_EXT_RFENCE_REMOTE_SFENCE_VMA_ASID,
+		     hart_mask, 0, start, size, asid, 0);
 }
 EXPORT_SYMBOL(sbi_remote_sfence_vma_asid);
 
@@ -249,8 +331,15 @@ int __init sbi_init(void)
 
 	pr_info("SBI specification v%lu.%lu detected\n",
 		sbi_major_version(), sbi_minor_version());
-	if (!sbi_spec_is_0_1())
+
+	if (!sbi_spec_is_0_1()) {
 		pr_info("SBI implementation ID=0x%lx Version=0x%lx\n",
 			sbi_get_firmware_id(), sbi_get_firmware_version());
+	}
+
+	__sbi_set_timer = __sbi_set_timer_v01;
+	__sbi_send_ipi	= __sbi_send_ipi_v01;
+	__sbi_rfence	= __sbi_rfence_v01;
+
 	return 0;
 }
-- 
2.24.0



^ permalink raw reply	[flat|nested] 10+ messages in thread

* [PATCH v6 5/5] RISC-V: Implement new SBI v0.2 extensions
  2019-12-18 21:39 [PATCH v6 0/5] Add support for SBI v0.2 Atish Patra
                   ` (3 preceding siblings ...)
  2019-12-18 21:39 ` [PATCH v6 4/5] RISC-V: Introduce a new config for SBI v0.1 Atish Patra
@ 2019-12-18 21:39 ` Atish Patra
  2020-01-15 20:34 ` [PATCH v6 3/5] RISC-V: Add SBI v0.2 extension definitions Palmer Dabbelt
  2020-01-15 20:36 ` [PATCH v6 0/5] Add support for SBI v0.2 Palmer Dabbelt
  6 siblings, 0 replies; 10+ messages in thread
From: Atish Patra @ 2019-12-18 21:39 UTC (permalink / raw)
  To: linux-kernel
  Cc: Albert Ou, Anup Patel, Atish Patra, Mike Rapoport, Atish Patra,
	Palmer Dabbelt, Paul Walmsley, Palmer Dabbelt, linux-riscv,
	Thomas Gleixner

Few v0.1 SBI calls are being replaced by new SBI calls that follows v0.2
calling convention.

Implement the replacement extensions and few additional new SBI function calls
that makes way for a better SBI interface in future.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
---
 arch/riscv/include/asm/sbi.h |  14 +++
 arch/riscv/kernel/sbi.c      | 198 ++++++++++++++++++++++++++++++++++-
 2 files changed, 208 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 89a25a049d12..e5569e7fdd7c 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -96,6 +96,20 @@ void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
 				unsigned long start,
 				unsigned long size,
 				unsigned long asid);
+int sbi_remote_hfence_gvma(const unsigned long *hart_mask,
+			   unsigned long start,
+			   unsigned long size);
+int sbi_remote_hfence_gvma_vmid(const unsigned long *hart_mask,
+				unsigned long start,
+				unsigned long size,
+				unsigned long vmid);
+int sbi_remote_hfence_vvma(const unsigned long *hart_mask,
+			   unsigned long start,
+			   unsigned long size);
+int sbi_remote_hfence_vvma_asid(const unsigned long *hart_mask,
+				unsigned long start,
+				unsigned long size,
+				unsigned long asid);
 int sbi_probe_extension(int ext);
 
 /* Check if current SBI specification version is 0.1 or not */
diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
index 265637cb5eb0..a1f2fca11f71 100644
--- a/arch/riscv/kernel/sbi.c
+++ b/arch/riscv/kernel/sbi.c
@@ -193,6 +193,102 @@ static int __sbi_rfence_v01(int fid,
 }
 #endif /* CONFIG_RISCV_SBI_V01 */
 
+static void __sbi_set_timer_v02(uint64_t stime_value)
+{
+#if __riscv_xlen == 32
+	sbi_ecall(SBI_EXT_TIME, SBI_EXT_TIME_SET_TIMER, stime_value,
+			  stime_value >> 32, 0, 0, 0, 0);
+#else
+	sbi_ecall(SBI_EXT_TIME, SBI_EXT_TIME_SET_TIMER, stime_value, 0,
+		  0, 0, 0, 0);
+#endif
+}
+
+static int __sbi_send_ipi_v02(const unsigned long *hart_mask)
+{
+	unsigned long hmask_val;
+	struct cpumask tmask;
+	struct sbiret ret = {0};
+	int result;
+
+	if (!hart_mask) {
+		riscv_cpuid_to_hartid_mask(cpu_online_mask, &tmask);
+		hmask_val = *(cpumask_bits(&tmask));
+	} else
+		hmask_val = *hart_mask;
+
+	ret = sbi_ecall(SBI_EXT_IPI, SBI_EXT_IPI_SEND_IPI, hmask_val,
+			0, 0, 0, 0, 0);
+	if (ret.error) {
+		result = sbi_err_map_linux_errno(ret.error);
+		pr_err("%s: failed with error [%d]\n", __func__, result);
+	} else
+		result = ret.value;
+
+	return result;
+}
+
+static int __sbi_rfence_v02(int fid, const unsigned long *hart_mask,
+			    unsigned long hbase, unsigned long start,
+			    unsigned long size, unsigned long arg4,
+			    unsigned long arg5)
+{
+	unsigned long hmask_val;
+	struct cpumask tmask;
+	struct sbiret ret = {0};
+	int ext = SBI_EXT_RFENCE;
+	int result;
+
+	if (!hart_mask) {
+		riscv_cpuid_to_hartid_mask(cpu_online_mask, &tmask);
+		hmask_val = *(cpumask_bits(&tmask));
+	} else
+		hmask_val = *hart_mask;
+
+	switch (fid) {
+	case SBI_EXT_RFENCE_REMOTE_FENCE_I:
+		ret = sbi_ecall(ext, fid, hmask_val, 0, 0, 0, 0, 0);
+		break;
+	case SBI_EXT_RFENCE_REMOTE_SFENCE_VMA:
+		ret = sbi_ecall(ext, fid, hmask_val, 0, start,
+				size, 0, 0);
+		break;
+	case SBI_EXT_RFENCE_REMOTE_SFENCE_VMA_ASID:
+		ret = sbi_ecall(ext, fid, hmask_val, 0, start,
+				size, arg4, 0);
+		break;
+	/*TODO: Handle non zero hbase cases */
+	case SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA:
+		ret = sbi_ecall(ext, fid, hmask_val, 0, start,
+				size, 0, 0);
+		break;
+	case SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA_VMID:
+		ret = sbi_ecall(ext, fid, hmask_val, 0, start,
+				size, arg4, 0);
+		break;
+	case SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA:
+		ret = sbi_ecall(ext, fid, hmask_val, 0, start,
+				size, 0, 0);
+		break;
+	case SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA_ASID:
+		ret = sbi_ecall(ext, fid, hmask_val, 0, start,
+				size, arg4, 0);
+		break;
+	default:
+		pr_err("unknown function ID [%d] for SBI extension [%d]\n",
+			fid, ext);
+		result = -EINVAL;
+	}
+
+	if (ret.error) {
+		result = sbi_err_map_linux_errno(ret.error);
+		pr_err("%s: failed with error [%d]\n", __func__, result);
+	} else
+		result = ret.value;
+
+	return result;
+}
+
 /**
  * sbi_set_timer() - Program the timer for next timer event.
  * @stime_value: The value after which next timer event should fire.
@@ -269,6 +365,85 @@ void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
 }
 EXPORT_SYMBOL(sbi_remote_sfence_vma_asid);
 
+/**
+ * sbi_remote_hfence_gvma() - Execute HFENCE.GVMA instructions on given remote
+ *			   harts for the specified guest physical address range.
+ * @hart_mask: A cpu mask containing all the target harts.
+ * @start: Start of the guest physical address
+ * @size: Total size of the guest physical address range.
+ *
+ * Return: None
+ */
+int sbi_remote_hfence_gvma(const unsigned long *hart_mask,
+					 unsigned long start,
+					 unsigned long size)
+{
+	return __sbi_rfence(SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA,
+			    hart_mask, 0, start, size, 0, 0);
+}
+EXPORT_SYMBOL_GPL(sbi_remote_hfence_gvma);
+
+/**
+ * sbi_remote_hfence_gvma_vmid() - Execute HFENCE.GVMA instructions on given
+ * remote harts for a guest physical address range belonging to a specific VMID.
+ *
+ * @hart_mask: A cpu mask containing all the target harts.
+ * @start: Start of the guest physical address
+ * @size: Total size of the guest physical address range.
+ * @vmid: The value of guest ID (VMID).
+ *
+ * Return: 0 if success, Error otherwise.
+ */
+int sbi_remote_hfence_gvma_vmid(const unsigned long *hart_mask,
+					      unsigned long start,
+					      unsigned long size,
+					      unsigned long vmid)
+{
+	return __sbi_rfence(SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA_VMID,
+			    hart_mask, 0, start, size, vmid, 0);
+}
+EXPORT_SYMBOL(sbi_remote_hfence_gvma_vmid);
+
+/**
+ * sbi_remote_hfence_vvma() - Execute HFENCE.VVMA instructions on given remote
+ *			     harts for the current guest virtual address range.
+ * @hart_mask: A cpu mask containing all the target harts.
+ * @start: Start of the current guest virtual address
+ * @size: Total size of the current guest virtual address range.
+ *
+ * Return: None
+ */
+int sbi_remote_hfence_vvma(const unsigned long *hart_mask,
+					 unsigned long start,
+					 unsigned long size)
+{
+	return __sbi_rfence(SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA,
+			    hart_mask, 0, start, size, 0, 0);
+}
+EXPORT_SYMBOL(sbi_remote_hfence_vvma);
+
+/**
+ * sbi_remote_hfence_vvma_asid() - Execute HFENCE.VVMA instructions on given
+ * remote harts for current guest virtual address range belonging to a specific
+ * ASID.
+ *
+ * @hart_mask: A cpu mask containing all the target harts.
+ * @start: Start of the current guest virtual address
+ * @size: Total size of the current guest virtual address range.
+ * @asid: The value of address space identifier (ASID).
+ *
+ * Return: None
+ */
+int sbi_remote_hfence_vvma_asid(const unsigned long *hart_mask,
+					      unsigned long start,
+					      unsigned long size,
+					      unsigned long asid)
+{
+	return __sbi_rfence(SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA_ASID,
+			    hart_mask, 0, start, size, asid, 0);
+}
+EXPORT_SYMBOL(sbi_remote_hfence_vvma_asid);
+
 /**
  * sbi_probe_extension() - Check if an SBI extension ID is supported or not.
  * @extid: The extension ID to be probed.
@@ -335,11 +510,26 @@ int __init sbi_init(void)
 	if (!sbi_spec_is_0_1()) {
 		pr_info("SBI implementation ID=0x%lx Version=0x%lx\n",
 			sbi_get_firmware_id(), sbi_get_firmware_version());
+		if (sbi_probe_extension(SBI_EXT_TIME) > 0) {
+			__sbi_set_timer = __sbi_set_timer_v02;
+			pr_info("SBI v0.2 TIME extension detected\n");
+		} else
+			__sbi_set_timer = __sbi_set_timer_v01;
+		if (sbi_probe_extension(SBI_EXT_IPI) > 0) {
+			__sbi_send_ipi	= __sbi_send_ipi_v02;
+			pr_info("SBI v0.2 IPI extension detected\n");
+		} else
+			__sbi_send_ipi	= __sbi_send_ipi_v01;
+		if (sbi_probe_extension(SBI_EXT_RFENCE) > 0) {
+			__sbi_rfence	= __sbi_rfence_v02;
+			pr_info("SBI v0.2 RFENCE extension detected\n");
+		} else
+			__sbi_rfence	= __sbi_rfence_v01;
+	} else {
+		__sbi_set_timer = __sbi_set_timer_v01;
+		__sbi_send_ipi	= __sbi_send_ipi_v01;
+		__sbi_rfence	= __sbi_rfence_v01;
 	}
 
-	__sbi_set_timer = __sbi_set_timer_v01;
-	__sbi_send_ipi	= __sbi_send_ipi_v01;
-	__sbi_rfence	= __sbi_rfence_v01;
-
 	return 0;
 }
-- 
2.24.0



^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH v6 3/5] RISC-V: Add SBI v0.2 extension definitions
  2019-12-18 21:39 ` [PATCH v6 3/5] RISC-V: Add SBI v0.2 extension definitions Atish Patra
@ 2019-12-19  6:55   ` Anup Patel
  0 siblings, 0 replies; 10+ messages in thread
From: Anup Patel @ 2019-12-19  6:55 UTC (permalink / raw)
  To: Atish Patra
  Cc: Albert Ou, Atish Patra, linux-kernel@vger.kernel.org List,
	Mike Rapoport, Palmer Dabbelt, Paul Walmsley, Palmer Dabbelt,
	linux-riscv, Thomas Gleixner

On Thu, Dec 19, 2019 at 3:09 AM Atish Patra <atish.patra@wdc.com> wrote:
>
> Few v0.1 SBI calls are being replaced by new SBI calls that follows
> v0.2 calling convention.
>
> This patch just defines these new extensions.
>
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> ---
>  arch/riscv/include/asm/sbi.h | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
>
> diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> index 1aeb4bb7baa8..9612133213ba 100644
> --- a/arch/riscv/include/asm/sbi.h
> +++ b/arch/riscv/include/asm/sbi.h
> @@ -21,6 +21,9 @@ enum sbi_ext_id {
>         SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID = 0x7,
>         SBI_EXT_0_1_SHUTDOWN = 0x8,
>         SBI_EXT_BASE = 0x10,
> +       SBI_EXT_TIME = 0x54494D45,
> +       SBI_EXT_IPI = 0x735049,
> +       SBI_EXT_RFENCE = 0x52464E43,
>  };
>
>  enum sbi_ext_base_fid {
> @@ -33,6 +36,24 @@ enum sbi_ext_base_fid {
>         SBI_EXT_BASE_GET_MIMPID,
>  };
>
> +enum sbi_ext_time_fid {
> +       SBI_EXT_TIME_SET_TIMER = 0,
> +};
> +
> +enum sbi_ext_ipi_fid {
> +       SBI_EXT_IPI_SEND_IPI = 0,
> +};
> +
> +enum sbi_ext_rfence_fid {
> +       SBI_EXT_RFENCE_REMOTE_FENCE_I = 0,
> +       SBI_EXT_RFENCE_REMOTE_SFENCE_VMA,
> +       SBI_EXT_RFENCE_REMOTE_SFENCE_VMA_ASID,
> +       SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA,
> +       SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA_VMID,
> +       SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA,
> +       SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA_ASID,
> +};
> +
>  #define SBI_SPEC_VERSION_DEFAULT       0x1
>  #define SBI_SPEC_VERSION_MAJOR_SHIFT   24
>  #define SBI_SPEC_VERSION_MAJOR_MASK    0x7f
> --
> 2.24.0
>

Looks good to me.

Reviewed-by: Anup Patel <anup@brainfault.org>

Regards,
Anup


^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH v6 3/5] RISC-V: Add SBI v0.2 extension definitions
  2019-12-18 21:39 [PATCH v6 0/5] Add support for SBI v0.2 Atish Patra
                   ` (4 preceding siblings ...)
  2019-12-18 21:39 ` [PATCH v6 5/5] RISC-V: Implement new SBI v0.2 extensions Atish Patra
@ 2020-01-15 20:34 ` Palmer Dabbelt
  2020-01-15 20:36 ` [PATCH v6 0/5] Add support for SBI v0.2 Palmer Dabbelt
  6 siblings, 0 replies; 10+ messages in thread
From: Palmer Dabbelt @ 2020-01-15 20:34 UTC (permalink / raw)
  To: Atish Patra
  Cc: aou, anup, atishp, linux-kernel, rppt, Atish Patra,
	Paul Walmsley, linux-riscv, tglx

On Wed, 18 Dec 2019 13:39:16 PST (-0800), Atish Patra wrote:
> Few v0.1 SBI calls are being replaced by new SBI calls that follows
> v0.2 calling convention.
>
> This patch just defines these new extensions.
>
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> ---
>  arch/riscv/include/asm/sbi.h | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
>
> diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> index 1aeb4bb7baa8..9612133213ba 100644
> --- a/arch/riscv/include/asm/sbi.h
> +++ b/arch/riscv/include/asm/sbi.h
> @@ -21,6 +21,9 @@ enum sbi_ext_id {
>  	SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID = 0x7,
>  	SBI_EXT_0_1_SHUTDOWN = 0x8,
>  	SBI_EXT_BASE = 0x10,
> +	SBI_EXT_TIME = 0x54494D45,
> +	SBI_EXT_IPI = 0x735049,
> +	SBI_EXT_RFENCE = 0x52464E43,
>  };
>
>  enum sbi_ext_base_fid {
> @@ -33,6 +36,24 @@ enum sbi_ext_base_fid {
>  	SBI_EXT_BASE_GET_MIMPID,
>  };
>
> +enum sbi_ext_time_fid {
> +	SBI_EXT_TIME_SET_TIMER = 0,
> +};
> +
> +enum sbi_ext_ipi_fid {
> +	SBI_EXT_IPI_SEND_IPI = 0,
> +};
> +
> +enum sbi_ext_rfence_fid {
> +	SBI_EXT_RFENCE_REMOTE_FENCE_I = 0,
> +	SBI_EXT_RFENCE_REMOTE_SFENCE_VMA,
> +	SBI_EXT_RFENCE_REMOTE_SFENCE_VMA_ASID,
> +	SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA,
> +	SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA_VMID,
> +	SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA,
> +	SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA_ASID,
> +};
> +
>  #define SBI_SPEC_VERSION_DEFAULT	0x1
>  #define SBI_SPEC_VERSION_MAJOR_SHIFT	24
>  #define SBI_SPEC_VERSION_MAJOR_MASK	0x7f

With or without SBI_EXT_RFENCE_*, depending on what we do with the spec:

Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>


^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH v6 0/5] Add support for SBI v0.2
  2019-12-18 21:39 [PATCH v6 0/5] Add support for SBI v0.2 Atish Patra
                   ` (5 preceding siblings ...)
  2020-01-15 20:34 ` [PATCH v6 3/5] RISC-V: Add SBI v0.2 extension definitions Palmer Dabbelt
@ 2020-01-15 20:36 ` Palmer Dabbelt
  2020-01-16  0:43   ` Anup Patel
  6 siblings, 1 reply; 10+ messages in thread
From: Palmer Dabbelt @ 2020-01-15 20:36 UTC (permalink / raw)
  To: Atish Patra
  Cc: aou, anup, atishp, linux-kernel, rppt, Atish Patra,
	Paul Walmsley, linux-riscv, tglx

On Wed, 18 Dec 2019 13:39:13 PST (-0800), Atish Patra wrote:
> The Supervisor Binary Interface(SBI) specification[1] now defines a
> base extension that provides extendability to add future extensions
> while maintaining backward compatibility with previous versions.
> The new version is defined as 0.2 and older version is marked as 0.1.
>
>
> This series adds support v0.2 and a unified calling convention
> implementation between 0.1 and 0.2. It also add other SBI v0.2
> functionality defined in [2]. The base support for SBI v0.2 is already
> available in OpenSBI v0.5. This series needs additional patches[3] in
> OpenSBI.
>
> Tested on both BBL, OpenSBI with/without the above patch series.
>
> [1] https://github.com/riscv/riscv-sbi-doc/blob/master/riscv-sbi.adoc
> [2] https://github.com/riscv/riscv-sbi-doc/pull/27
> [3] http://lists.infradead.org/pipermail/opensbi/2019-November/000738.html
>
> Changes from v5->v6
> 1. Fixed few compilation issues around config.
> 2. Fixed hart mask generation issues for RFENCE & IPI extensions.
>
> Changes from v4->v5
> 1. Fixed few minor comments related to static & inline.
> 2. Make sure that every patch is boot tested individually.
>
> Changes from v3->v4.
> 1. Rebased on for-next.
> 2. Fixed issuses with checkpatch --strict.
> 3. Unfied all IPI/fence related functions.
> 4. Added Hfence related SBI calls.
>
> Changes from v2->v3.
> 1. Moved v0.1 extensions to a new config.
> 2. Added support for relacement extensions of v0.1 extensions.
>
> Changes from v1->v2
> 1. Removed the legacy calling convention.
> 2. Moved all SBI related calls to sbi.c.
> 3. Moved all SBI related macros to uapi.
>
> Atish Patra (5):
> RISC-V: Mark existing SBI as 0.1 SBI.
> RISC-V: Add basic support for SBI v0.2
> RISC-V: Add SBI v0.2 extension definitions
> RISC-V: Introduce a new config for SBI v0.1
> RISC-V: Implement new SBI v0.2 extensions
>
> arch/riscv/Kconfig           |   6 +
> arch/riscv/include/asm/sbi.h | 178 +++++++-----
> arch/riscv/kernel/sbi.c      | 522 ++++++++++++++++++++++++++++++++++-
> arch/riscv/kernel/setup.c    |   2 +
> 4 files changed, 635 insertions(+), 73 deletions(-)

Thanks.  I had a few comments on the spec, but this looks good given what's in
the draft.


^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [PATCH v6 0/5] Add support for SBI v0.2
  2020-01-15 20:36 ` [PATCH v6 0/5] Add support for SBI v0.2 Palmer Dabbelt
@ 2020-01-16  0:43   ` Anup Patel
  0 siblings, 0 replies; 10+ messages in thread
From: Anup Patel @ 2020-01-16  0:43 UTC (permalink / raw)
  To: Palmer Dabbelt
  Cc: Albert Ou, Atish Patra, linux-kernel@vger.kernel.org List,
	Mike Rapoport, Atish Patra, Paul Walmsley, linux-riscv,
	Thomas Gleixner

On Thu, Jan 16, 2020 at 2:06 AM Palmer Dabbelt <palmerdabbelt@google.com> wrote:
>
> On Wed, 18 Dec 2019 13:39:13 PST (-0800), Atish Patra wrote:
> > The Supervisor Binary Interface(SBI) specification[1] now defines a
> > base extension that provides extendability to add future extensions
> > while maintaining backward compatibility with previous versions.
> > The new version is defined as 0.2 and older version is marked as 0.1.
> >
> >
> > This series adds support v0.2 and a unified calling convention
> > implementation between 0.1 and 0.2. It also add other SBI v0.2
> > functionality defined in [2]. The base support for SBI v0.2 is already
> > available in OpenSBI v0.5. This series needs additional patches[3] in
> > OpenSBI.
> >
> > Tested on both BBL, OpenSBI with/without the above patch series.
> >
> > [1] https://github.com/riscv/riscv-sbi-doc/blob/master/riscv-sbi.adoc
> > [2] https://github.com/riscv/riscv-sbi-doc/pull/27
> > [3] http://lists.infradead.org/pipermail/opensbi/2019-November/000738.html
> >
> > Changes from v5->v6
> > 1. Fixed few compilation issues around config.
> > 2. Fixed hart mask generation issues for RFENCE & IPI extensions.
> >
> > Changes from v4->v5
> > 1. Fixed few minor comments related to static & inline.
> > 2. Make sure that every patch is boot tested individually.
> >
> > Changes from v3->v4.
> > 1. Rebased on for-next.
> > 2. Fixed issuses with checkpatch --strict.
> > 3. Unfied all IPI/fence related functions.
> > 4. Added Hfence related SBI calls.
> >
> > Changes from v2->v3.
> > 1. Moved v0.1 extensions to a new config.
> > 2. Added support for relacement extensions of v0.1 extensions.
> >
> > Changes from v1->v2
> > 1. Removed the legacy calling convention.
> > 2. Moved all SBI related calls to sbi.c.
> > 3. Moved all SBI related macros to uapi.
> >
> > Atish Patra (5):
> > RISC-V: Mark existing SBI as 0.1 SBI.
> > RISC-V: Add basic support for SBI v0.2
> > RISC-V: Add SBI v0.2 extension definitions
> > RISC-V: Introduce a new config for SBI v0.1
> > RISC-V: Implement new SBI v0.2 extensions
> >
> > arch/riscv/Kconfig           |   6 +
> > arch/riscv/include/asm/sbi.h | 178 +++++++-----
> > arch/riscv/kernel/sbi.c      | 522 ++++++++++++++++++++++++++++++++++-
> > arch/riscv/kernel/setup.c    |   2 +
> > 4 files changed, 635 insertions(+), 73 deletions(-)
>
> Thanks.  I had a few comments on the spec, but this looks good given what's in
> the draft.

For the benefit of people not watching GitHub SBI spec comments, here
are my comments as replied on GitHub as well.


Palmer Dabbelt <palmerdabbelt@google.com> wrote on GitHub:
> After looking into some of the remote fence instruction stuff I really don't think we're ready to define an SBI extension here. I'm specifically worried about all these fences being one-sided (ie, blocking), which probably isn't what you want for remote fences.

The blocking nature of remote TLB flushes is as-per expectation of
Linux kernel and it is also true for IPI based remote TLB flushes.
In trying to fix Glibc craches with OpenSBI (six months back), we
realized that non-blocking remote TLB flushes with SBI calls (or with
IPIs) causes Linux kernel to crash because if we return before TLBs
on other HARTs are updated then other HARTs can potentially do invalid
access using stale TLB enteries. Due to this reason, on architecutures
(such as ARM64) with ISA support for remote TLB flush, the remote TLB
flush instructions are defined as blocking. The IPI based remote TLB
flushes for x86_64 is also blocking.
(Refer, https://github.com/torvalds/linux/blob/master/arch/x86/mm/tlb.c#L708)

> IIRC we'd decided at the Zurich workshop to stop speculatively defining SBI extensions until we had a corresponding ISA extension that would make them somehow better to implement in M-mode than in S-mode, and I think this extension is a good one to wait on.

IIRC, (at Zurich workshop 2019) we had decided to keep remote TLB flush
calls as optional (and not remove it) so that in-future an ISA extension
can be defined and preferred over SBI call.

The rational for above (as discussed at Zurich workshop 2019) is:

1. If we don't have SBI extension and ISA extension for remote TLB
flush then Guest/VM don't have any way for remote TLB flushes. A
software emulated MMIO CLINT for Guest/VM is not a viable option
because to inject IPI to N HARTs we need to do N MMIO writes where
each MMIO write will be trap-n-emulated. This will be very slow
and not at all scalable for any hypervisor.

2. In absence of S-mode CLINT and remote TLB flush ISA extension,
the IPI based remote TLB flush will be quite slow compared to SBI
calls because each IPI call will again go through SBI call. We had
proven this fact using benchmarks as well. In fact, this performance
difference was discussed in Linux kernel mailing list long time back
(Refer https://patchwork.kernel.org/cover/10872349/). The newer SBI
RFENCE calls are even better than SBI v0.1 RFENCE calls because we
are avoiding unpriv access so with these new calls we will get even
better performance compared to IPI based remote TLB flushes.

3. The SBI extension for remote TLB flush does not remove the
possibility of defining an ISA extension in-future. In fact,
in-future the Linux kernel will decide at runtime on method to
use for remote TLB flushes as follows:
 a) First check if an ISA extension for remote TLB flush is
    available. If available then use it otherwise try step b
 b) Next check if S-mode CLINT is available. If available then
    use IPI based remote TLB flush otherwise try step c
 c) Lastly check if SBI RFENCE extension is available. If
    available then use it otherwise try step d
 d) We don't have any method for remote TLB flush so crash.

>
> Yes, that means than an SBI-0.2-clean Linux will need to handle these as IPIs, but I think that's actually a good thing: it avoids baking unknows into the ABI, which allows us to experiment more freely and ideally figure out the right way to do this more quickly.

Please see previous comments

Regards,
Anup


^ permalink raw reply	[flat|nested] 10+ messages in thread

end of thread, other threads:[~2020-01-16  0:43 UTC | newest]

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2019-12-18 21:39 [PATCH v6 0/5] Add support for SBI v0.2 Atish Patra
2019-12-18 21:39 ` [PATCH v6 1/5] RISC-V: Mark existing SBI as 0.1 SBI Atish Patra
2019-12-18 21:39 ` [PATCH v6 2/5] RISC-V: Add basic support for SBI v0.2 Atish Patra
2019-12-18 21:39 ` [PATCH v6 3/5] RISC-V: Add SBI v0.2 extension definitions Atish Patra
2019-12-19  6:55   ` Anup Patel
2019-12-18 21:39 ` [PATCH v6 4/5] RISC-V: Introduce a new config for SBI v0.1 Atish Patra
2019-12-18 21:39 ` [PATCH v6 5/5] RISC-V: Implement new SBI v0.2 extensions Atish Patra
2020-01-15 20:34 ` [PATCH v6 3/5] RISC-V: Add SBI v0.2 extension definitions Palmer Dabbelt
2020-01-15 20:36 ` [PATCH v6 0/5] Add support for SBI v0.2 Palmer Dabbelt
2020-01-16  0:43   ` Anup Patel

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