[kvm-unit-tests PATCH v5 0/5] riscv: sbi: Add support to test timer extension

[kvm-unit-tests PATCH v5 0/5] riscv: sbi: Add support to test timer extension

[James Raphael Tiovalen]

This patch series adds support for testing the timer extension as
defined in the RISC-V SBI specification. The first 2 patches add
infrastructural support for handling interrupts, the next 2 patches add
some helper routines that can be used by SBI extension tests, while the
last patch adds the actual test for the timer extension.

v5:
- Addressed all of Andrew's comments on v4.
- Updated the test to check if `sip.STIP` is cleared for both cases of
  setting the timer to -1 and masking the timer irq as per the spec.
- Updated the test to check if `sie.STIE` is writable for the mask irq
  test.

v4:
- Addressed all of Andrew's comments on v3.

v3:
- Addressed all of Andrew's comments on v2.
- Added 2 new patches to add sbi_probe and the delay and timer routines.

v2:
- Addressed all of the previous comments from Andrew.
- Updated the test to get the timer frequency value from the device tree
  and allow the test parameters to be specified in microseconds instead of
  cycles.

Andrew Jones (1):
  riscv: Extend exception handling support for interrupts

James Raphael Tiovalen (4):
  riscv: Update exception cause list
  riscv: Add method to probe for SBI extensions
  riscv: Add some delay and timer routines
  riscv: sbi: Add test for timer extension

 riscv/Makefile            |   2 +
 lib/riscv/asm/csr.h       |  21 ++++++
 lib/riscv/asm/delay.h     |  16 +++++
 lib/riscv/asm/processor.h |  15 +++-
 lib/riscv/asm/sbi.h       |   6 ++
 lib/riscv/asm/setup.h     |   1 +
 lib/riscv/asm/timer.h     |  24 +++++++
 lib/riscv/delay.c         |  21 ++++++
 lib/riscv/processor.c     |  27 +++++--
 lib/riscv/sbi.c           |  13 ++++
 lib/riscv/setup.c         |   4 ++
 lib/riscv/timer.c         |  28 ++++++++
 riscv/sbi.c               | 144 ++++++++++++++++++++++++++++++++++++++
 13 files changed, 317 insertions(+), 5 deletions(-)
 create mode 100644 lib/riscv/asm/delay.h
 create mode 100644 lib/riscv/asm/timer.h
 create mode 100644 lib/riscv/delay.c
 create mode 100644 lib/riscv/timer.c

--
2.43.0

[kvm-unit-tests PATCH v5 1/5] riscv: Extend exception handling support for interrupts

[James Raphael Tiovalen]

From: Andrew Jones <andrew.jones@linux.dev>

Add install_irq_handler() to enable tests to install interrupt handlers.
Also add local_irq_enable() and local_irq_disable() to respectively
enable and disable IRQs via the sstatus.SIE bit.

Signed-off-by: Andrew Jones <andrew.jones@linux.dev>
Signed-off-by: James Raphael Tiovalen <jamestiotio@gmail.com>
---
 lib/riscv/asm/csr.h       |  2 ++
 lib/riscv/asm/processor.h | 13 +++++++++++++
 lib/riscv/processor.c     | 27 +++++++++++++++++++++++----
 3 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/lib/riscv/asm/csr.h b/lib/riscv/asm/csr.h
index 52608512..d6909d93 100644
--- a/lib/riscv/asm/csr.h
+++ b/lib/riscv/asm/csr.h
@@ -11,6 +11,8 @@
 #define CSR_STVAL		0x143
 #define CSR_SATP		0x180
 
+#define SR_SIE			_AC(0x00000002, UL)
+
 /* Exception cause high bit - is an interrupt if set */
 #define CAUSE_IRQ_FLAG		(_AC(1, UL) << (__riscv_xlen - 1))
 
diff --git a/lib/riscv/asm/processor.h b/lib/riscv/asm/processor.h
index 32c499d0..6451adb5 100644
--- a/lib/riscv/asm/processor.h
+++ b/lib/riscv/asm/processor.h
@@ -5,6 +5,7 @@
 #include <asm/ptrace.h>
 
 #define EXCEPTION_CAUSE_MAX	16
+#define INTERRUPT_CAUSE_MAX	16
 
 typedef void (*exception_fn)(struct pt_regs *);
 
@@ -13,6 +14,7 @@ struct thread_info {
 	unsigned long hartid;
 	unsigned long isa[1];
 	exception_fn exception_handlers[EXCEPTION_CAUSE_MAX];
+	exception_fn interrupt_handlers[INTERRUPT_CAUSE_MAX];
 };
 
 static inline struct thread_info *current_thread_info(void)
@@ -20,7 +22,18 @@ static inline struct thread_info *current_thread_info(void)
 	return (struct thread_info *)csr_read(CSR_SSCRATCH);
 }
 
+static inline void local_irq_enable(void)
+{
+	csr_set(CSR_SSTATUS, SR_SIE);
+}
+
+static inline void local_irq_disable(void)
+{
+	csr_clear(CSR_SSTATUS, SR_SIE);
+}
+
 void install_exception_handler(unsigned long cause, void (*handler)(struct pt_regs *));
+void install_irq_handler(unsigned long cause, void (*handler)(struct pt_regs *));
 void do_handle_exception(struct pt_regs *regs);
 void thread_info_init(void);
 
diff --git a/lib/riscv/processor.c b/lib/riscv/processor.c
index ece7cbff..0dffadc7 100644
--- a/lib/riscv/processor.c
+++ b/lib/riscv/processor.c
@@ -36,10 +36,21 @@ void do_handle_exception(struct pt_regs *regs)
 {
 	struct thread_info *info = current_thread_info();
 
-	assert(regs->cause < EXCEPTION_CAUSE_MAX);
-	if (info->exception_handlers[regs->cause]) {
-		info->exception_handlers[regs->cause](regs);
-		return;
+	if (regs->cause & CAUSE_IRQ_FLAG) {
+		unsigned long irq_cause = regs->cause & ~CAUSE_IRQ_FLAG;
+
+		assert(irq_cause < INTERRUPT_CAUSE_MAX);
+		if (info->interrupt_handlers[irq_cause]) {
+			info->interrupt_handlers[irq_cause](regs);
+			return;
+		}
+	} else {
+		assert(regs->cause < EXCEPTION_CAUSE_MAX);
+
+		if (info->exception_handlers[regs->cause]) {
+			info->exception_handlers[regs->cause](regs);
+			return;
+		}
 	}
 
 	show_regs(regs);
@@ -47,6 +58,14 @@ void do_handle_exception(struct pt_regs *regs)
 	abort();
 }
 
+void install_irq_handler(unsigned long cause, void (*handler)(struct pt_regs *))
+{
+	struct thread_info *info = current_thread_info();
+
+	assert(cause < INTERRUPT_CAUSE_MAX);
+	info->interrupt_handlers[cause] = handler;
+}
+
 void install_exception_handler(unsigned long cause, void (*handler)(struct pt_regs *))
 {
 	struct thread_info *info = current_thread_info();
-- 
2.43.0

[kvm-unit-tests PATCH v5 2/5] riscv: Update exception cause list

[James Raphael Tiovalen]

Update the list of exception and interrupt causes to follow the latest
RISC-V privileged ISA specification (version 20240411 section 18.6.1).

Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Signed-off-by: James Raphael Tiovalen <jamestiotio@gmail.com>
---
 lib/riscv/asm/csr.h       | 10 ++++++++++
 lib/riscv/asm/processor.h |  2 +-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/lib/riscv/asm/csr.h b/lib/riscv/asm/csr.h
index d6909d93..ba810c9f 100644
--- a/lib/riscv/asm/csr.h
+++ b/lib/riscv/asm/csr.h
@@ -36,6 +36,16 @@
 #define EXC_VIRTUAL_INST_FAULT		22
 #define EXC_STORE_GUEST_PAGE_FAULT	23
 
+/* Interrupt causes */
+#define IRQ_S_SOFT		1
+#define IRQ_VS_SOFT		2
+#define IRQ_S_TIMER		5
+#define IRQ_VS_TIMER		6
+#define IRQ_S_EXT		9
+#define IRQ_VS_EXT		10
+#define IRQ_S_GEXT		12
+#define IRQ_PMU_OVF		13
+
 #ifndef __ASSEMBLY__
 
 #define csr_swap(csr, val)					\
diff --git a/lib/riscv/asm/processor.h b/lib/riscv/asm/processor.h
index 6451adb5..4c9ad968 100644
--- a/lib/riscv/asm/processor.h
+++ b/lib/riscv/asm/processor.h
@@ -4,7 +4,7 @@
 #include <asm/csr.h>
 #include <asm/ptrace.h>
 
-#define EXCEPTION_CAUSE_MAX	16
+#define EXCEPTION_CAUSE_MAX	24
 #define INTERRUPT_CAUSE_MAX	16
 
 typedef void (*exception_fn)(struct pt_regs *);
-- 
2.43.0

[kvm-unit-tests PATCH v5 3/5] riscv: Add method to probe for SBI extensions

[James Raphael Tiovalen]

Add a `sbi_probe` helper method that can be used by SBI extension tests
to check if a given extension is available.

Suggested-by: Andrew Jones <andrew.jones@linux.dev>
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Signed-off-by: James Raphael Tiovalen <jamestiotio@gmail.com>
---
 lib/riscv/asm/sbi.h |  1 +
 lib/riscv/sbi.c     | 13 +++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/lib/riscv/asm/sbi.h b/lib/riscv/asm/sbi.h
index d82a384d..5e1a674a 100644
--- a/lib/riscv/asm/sbi.h
+++ b/lib/riscv/asm/sbi.h
@@ -49,6 +49,7 @@ struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
 
 void sbi_shutdown(void);
 struct sbiret sbi_hart_start(unsigned long hartid, unsigned long entry, unsigned long sp);
+long sbi_probe(int ext);
 
 #endif /* !__ASSEMBLY__ */
 #endif /* _ASMRISCV_SBI_H_ */
diff --git a/lib/riscv/sbi.c b/lib/riscv/sbi.c
index f39134c4..3d4236e5 100644
--- a/lib/riscv/sbi.c
+++ b/lib/riscv/sbi.c
@@ -38,3 +38,16 @@ struct sbiret sbi_hart_start(unsigned long hartid, unsigned long entry, unsigned
 {
 	return sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_START, hartid, entry, sp, 0, 0, 0);
 }
+
+long sbi_probe(int ext)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_BASE, SBI_EXT_BASE_GET_SPEC_VERSION, 0, 0, 0, 0, 0, 0);
+	assert(!ret.error && ret.value >= 2);
+
+	ret = sbi_ecall(SBI_EXT_BASE, SBI_EXT_BASE_PROBE_EXT, ext, 0, 0, 0, 0, 0);
+	assert(!ret.error);
+
+	return ret.value;
+}
-- 
2.43.0

[kvm-unit-tests PATCH v5 4/5] riscv: Add some delay and timer routines

[James Raphael Tiovalen]

Add a delay method that would allow tests to wait for some specified
number of cycles. Also add a conversion helper method between
microseconds and cycles. This conversion is done by using the timebase
frequency, which is obtained during setup via the device tree.

Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Signed-off-by: James Raphael Tiovalen <jamestiotio@gmail.com>
---
 riscv/Makefile        |  2 ++
 lib/riscv/asm/csr.h   |  1 +
 lib/riscv/asm/delay.h | 16 ++++++++++++++++
 lib/riscv/asm/setup.h |  1 +
 lib/riscv/asm/timer.h | 14 ++++++++++++++
 lib/riscv/delay.c     | 21 +++++++++++++++++++++
 lib/riscv/setup.c     |  4 ++++
 lib/riscv/timer.c     | 28 ++++++++++++++++++++++++++++
 8 files changed, 87 insertions(+)
 create mode 100644 lib/riscv/asm/delay.h
 create mode 100644 lib/riscv/asm/timer.h
 create mode 100644 lib/riscv/delay.c
 create mode 100644 lib/riscv/timer.c

diff --git a/riscv/Makefile b/riscv/Makefile
index 919a3ebb..b0cd613f 100644
--- a/riscv/Makefile
+++ b/riscv/Makefile
@@ -30,6 +30,7 @@ cflatobjs += lib/memregions.o
 cflatobjs += lib/on-cpus.o
 cflatobjs += lib/vmalloc.o
 cflatobjs += lib/riscv/bitops.o
+cflatobjs += lib/riscv/delay.o
 cflatobjs += lib/riscv/io.o
 cflatobjs += lib/riscv/isa.o
 cflatobjs += lib/riscv/mmu.o
@@ -38,6 +39,7 @@ cflatobjs += lib/riscv/sbi.o
 cflatobjs += lib/riscv/setup.o
 cflatobjs += lib/riscv/smp.o
 cflatobjs += lib/riscv/stack.o
+cflatobjs += lib/riscv/timer.o
 ifeq ($(ARCH),riscv32)
 cflatobjs += lib/ldiv32.o
 endif
diff --git a/lib/riscv/asm/csr.h b/lib/riscv/asm/csr.h
index ba810c9f..a9b1bd42 100644
--- a/lib/riscv/asm/csr.h
+++ b/lib/riscv/asm/csr.h
@@ -10,6 +10,7 @@
 #define CSR_SCAUSE		0x142
 #define CSR_STVAL		0x143
 #define CSR_SATP		0x180
+#define CSR_TIME		0xc01
 
 #define SR_SIE			_AC(0x00000002, UL)
 
diff --git a/lib/riscv/asm/delay.h b/lib/riscv/asm/delay.h
new file mode 100644
index 00000000..31379eac
--- /dev/null
+++ b/lib/riscv/asm/delay.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _ASMRISCV_DELAY_H_
+#define _ASMRISCV_DELAY_H_
+
+#include <libcflat.h>
+#include <asm/setup.h>
+
+extern void delay(uint64_t cycles);
+extern void udelay(unsigned long usecs);
+
+static inline uint64_t usec_to_cycles(uint64_t usec)
+{
+	return (timebase_frequency * usec) / 1000000;
+}
+
+#endif /* _ASMRISCV_DELAY_H_ */
diff --git a/lib/riscv/asm/setup.h b/lib/riscv/asm/setup.h
index 7f81a705..a13159bf 100644
--- a/lib/riscv/asm/setup.h
+++ b/lib/riscv/asm/setup.h
@@ -7,6 +7,7 @@
 #define NR_CPUS 16
 extern struct thread_info cpus[NR_CPUS];
 extern int nr_cpus;
+extern uint64_t timebase_frequency;
 int hartid_to_cpu(unsigned long hartid);
 
 void io_init(void);
diff --git a/lib/riscv/asm/timer.h b/lib/riscv/asm/timer.h
new file mode 100644
index 00000000..f7504f84
--- /dev/null
+++ b/lib/riscv/asm/timer.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _ASMRISCV_TIMER_H_
+#define _ASMRISCV_TIMER_H_
+
+#include <asm/csr.h>
+
+extern void timer_get_frequency(void);
+
+static inline uint64_t timer_get_cycles(void)
+{
+	return csr_read(CSR_TIME);
+}
+
+#endif /* _ASMRISCV_TIMER_H_ */
diff --git a/lib/riscv/delay.c b/lib/riscv/delay.c
new file mode 100644
index 00000000..d4f76c29
--- /dev/null
+++ b/lib/riscv/delay.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2024, James Raphael Tiovalen <jamestiotio@gmail.com>
+ */
+#include <libcflat.h>
+#include <asm/barrier.h>
+#include <asm/delay.h>
+#include <asm/timer.h>
+
+void delay(uint64_t cycles)
+{
+	uint64_t start = timer_get_cycles();
+
+	while ((timer_get_cycles() - start) < cycles)
+		cpu_relax();
+}
+
+void udelay(unsigned long usecs)
+{
+	delay(usec_to_cycles((uint64_t)usecs));
+}
diff --git a/lib/riscv/setup.c b/lib/riscv/setup.c
index 50ffb0d0..e0b5f6f7 100644
--- a/lib/riscv/setup.c
+++ b/lib/riscv/setup.c
@@ -20,6 +20,7 @@
 #include <asm/page.h>
 #include <asm/processor.h>
 #include <asm/setup.h>
+#include <asm/timer.h>
 
 #define VA_BASE			((phys_addr_t)3 * SZ_1G)
 #if __riscv_xlen == 64
@@ -38,6 +39,7 @@ u32 initrd_size;
 
 struct thread_info cpus[NR_CPUS];
 int nr_cpus;
+uint64_t timebase_frequency;
 
 static struct mem_region riscv_mem_regions[NR_MEM_REGIONS + 1];
 
@@ -199,6 +201,7 @@ void setup(const void *fdt, phys_addr_t freemem_start)
 
 	mem_init(PAGE_ALIGN(__pa(freemem)));
 	cpu_init();
+	timer_get_frequency();
 	thread_info_init();
 	io_init();
 
@@ -264,6 +267,7 @@ efi_status_t setup_efi(efi_bootinfo_t *efi_bootinfo)
 	}
 
 	cpu_init();
+	timer_get_frequency();
 	thread_info_init();
 	io_init();
 	initrd_setup();
diff --git a/lib/riscv/timer.c b/lib/riscv/timer.c
new file mode 100644
index 00000000..d78d254c
--- /dev/null
+++ b/lib/riscv/timer.c
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2024, James Raphael Tiovalen <jamestiotio@gmail.com>
+ */
+#include <libcflat.h>
+#include <devicetree.h>
+#include <asm/setup.h>
+#include <asm/timer.h>
+
+void timer_get_frequency(void)
+{
+	const struct fdt_property *prop;
+	u32 *data;
+	int cpus, len;
+
+	assert_msg(dt_available(), "ACPI not yet supported");
+
+	const void *fdt = dt_fdt();
+
+	cpus = fdt_path_offset(fdt, "/cpus");
+	assert(cpus >= 0);
+
+	prop = fdt_get_property(fdt, cpus, "timebase-frequency", &len);
+	assert(prop != NULL && len == 4);
+
+	data = (u32 *)prop->data;
+	timebase_frequency = fdt32_to_cpu(*data);
+}
-- 
2.43.0

[kvm-unit-tests PATCH v5 5/5] riscv: sbi: Add test for timer extension

[James Raphael Tiovalen]

Add a test for the set_timer function of the time extension. The test
checks that:
- The time extension is available
- The installed timer interrupt handler is called
- The timer interrupt is received within a reasonable time interval
- The timer interrupt pending bit is cleared after the set_timer SBI
  call is made
- The timer interrupt can be cleared either by requesting a timer
  interrupt infinitely far into the future or by masking the timer
  interrupt

The timer interrupt delay can be set using the TIMER_DELAY environment
variable in microseconds. The default delay value is 200 milliseconds.
Since the interrupt can arrive a little later than the specified delay,
allow some margin of error. This margin of error can be specified via
the TIMER_MARGIN environment variable in microseconds. The default
margin of error is 200 milliseconds.

Signed-off-by: James Raphael Tiovalen <jamestiotio@gmail.com>
---
 lib/riscv/asm/csr.h   |   8 +++
 lib/riscv/asm/sbi.h   |   5 ++
 lib/riscv/asm/timer.h |  10 +++
 riscv/sbi.c           | 144 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 167 insertions(+)

diff --git a/lib/riscv/asm/csr.h b/lib/riscv/asm/csr.h
index a9b1bd42..24b333e0 100644
--- a/lib/riscv/asm/csr.h
+++ b/lib/riscv/asm/csr.h
@@ -4,11 +4,15 @@
 #include <linux/const.h>
 
 #define CSR_SSTATUS		0x100
+#define CSR_SIE			0x104
 #define CSR_STVEC		0x105
 #define CSR_SSCRATCH		0x140
 #define CSR_SEPC		0x141
 #define CSR_SCAUSE		0x142
 #define CSR_STVAL		0x143
+#define CSR_SIP			0x144
+#define CSR_STIMECMP		0x14d
+#define CSR_STIMECMPH		0x15d
 #define CSR_SATP		0x180
 #define CSR_TIME		0xc01
 
@@ -47,6 +51,10 @@
 #define IRQ_S_GEXT		12
 #define IRQ_PMU_OVF		13
 
+#define IE_TIE			(_AC(0x1, UL) << IRQ_S_TIMER)
+
+#define IP_TIP			IE_TIE
+
 #ifndef __ASSEMBLY__
 
 #define csr_swap(csr, val)					\
diff --git a/lib/riscv/asm/sbi.h b/lib/riscv/asm/sbi.h
index 5e1a674a..73ab5438 100644
--- a/lib/riscv/asm/sbi.h
+++ b/lib/riscv/asm/sbi.h
@@ -16,6 +16,7 @@
 
 enum sbi_ext_id {
 	SBI_EXT_BASE = 0x10,
+	SBI_EXT_TIME = 0x54494d45,
 	SBI_EXT_HSM = 0x48534d,
 	SBI_EXT_SRST = 0x53525354,
 };
@@ -37,6 +38,10 @@ enum sbi_ext_hsm_fid {
 	SBI_EXT_HSM_HART_SUSPEND,
 };
 
+enum sbi_ext_time_fid {
+	SBI_EXT_TIME_SET_TIMER = 0,
+};
+
 struct sbiret {
 	long error;
 	long value;
diff --git a/lib/riscv/asm/timer.h b/lib/riscv/asm/timer.h
index f7504f84..b3514d3f 100644
--- a/lib/riscv/asm/timer.h
+++ b/lib/riscv/asm/timer.h
@@ -11,4 +11,14 @@ static inline uint64_t timer_get_cycles(void)
 	return csr_read(CSR_TIME);
 }
 
+static inline void timer_irq_enable(void)
+{
+	csr_set(CSR_SIE, IE_TIE);
+}
+
+static inline void timer_irq_disable(void)
+{
+	csr_clear(CSR_SIE, IE_TIE);
+}
+
 #endif /* _ASMRISCV_TIMER_H_ */
diff --git a/riscv/sbi.c b/riscv/sbi.c
index 762e9711..044258bb 100644
--- a/riscv/sbi.c
+++ b/riscv/sbi.c
@@ -6,7 +6,25 @@
  */
 #include <libcflat.h>
 #include <stdlib.h>
+#include <limits.h>
+#include <asm/barrier.h>
+#include <asm/csr.h>
+#include <asm/delay.h>
+#include <asm/isa.h>
+#include <asm/processor.h>
 #include <asm/sbi.h>
+#include <asm/smp.h>
+#include <asm/timer.h>
+
+struct timer_info {
+	bool timer_works;
+	bool mask_timer_irq;
+	bool timer_irq_set;
+	bool timer_irq_cleared;
+	unsigned long timer_irq_count;
+};
+
+static struct timer_info timer_info_;
 
 static void help(void)
 {
@@ -19,6 +37,36 @@ static struct sbiret __base_sbi_ecall(int fid, unsigned long arg0)
 	return sbi_ecall(SBI_EXT_BASE, fid, arg0, 0, 0, 0, 0, 0);
 }
 
+static struct sbiret __time_sbi_ecall(unsigned long stime_value)
+{
+	return sbi_ecall(SBI_EXT_TIME, SBI_EXT_TIME_SET_TIMER, stime_value, 0, 0, 0, 0, 0);
+}
+
+static bool timer_irq_pending(void)
+{
+	return csr_read(CSR_SIP) & IP_TIP;
+}
+
+static void timer_irq_handler(struct pt_regs *regs)
+{
+	if (timer_info_.timer_irq_count < ULONG_MAX)
+		++timer_info_.timer_irq_count;
+
+	timer_info_.timer_works = true;
+	if (timer_irq_pending())
+		timer_info_.timer_irq_set = true;
+
+	if (timer_info_.mask_timer_irq) {
+		timer_irq_disable();
+		__time_sbi_ecall(0);
+	} else {
+		__time_sbi_ecall(ULONG_MAX);
+	}
+
+	if (!timer_irq_pending())
+		timer_info_.timer_irq_cleared = true;
+}
+
 static bool env_or_skip(const char *env)
 {
 	if (!getenv(env)) {
@@ -112,6 +160,101 @@ static void check_base(void)
 	report_prefix_pop();
 }
 
+static void check_time(void)
+{
+	struct sbiret ret;
+	unsigned long begin, end, duration;
+	unsigned long d = getenv("TIMER_DELAY") ? strtol(getenv("TIMER_DELAY"), NULL, 0)
+						: 200000;
+	unsigned long margin = getenv("TIMER_MARGIN") ? strtol(getenv("TIMER_MARGIN"), NULL, 0)
+						      : 200000;
+
+	d = usec_to_cycles(d);
+	margin = usec_to_cycles(margin);
+
+	report_prefix_push("time");
+
+	if (!sbi_probe(SBI_EXT_TIME)) {
+		report_skip("time extension not available");
+		report_prefix_pop();
+		return;
+	}
+
+	report_prefix_push("set_timer");
+
+	install_irq_handler(IRQ_S_TIMER, timer_irq_handler);
+	local_irq_enable();
+	if (cpu_has_extension(smp_processor_id(), ISA_SSTC)) {
+		csr_write(CSR_STIMECMP, ULONG_MAX);
+#if __riscv_xlen == 32
+		csr_write(CSR_STIMECMPH, ULONG_MAX);
+#endif
+	}
+	timer_irq_enable();
+
+	begin = timer_get_cycles();
+	ret = __time_sbi_ecall(begin + d);
+
+	report(!ret.error, "set timer");
+	if (ret.error)
+		report_info("set timer failed with %ld\n", ret.error);
+
+	report(!timer_irq_pending(), "pending timer interrupt bit cleared");
+
+	while ((end = timer_get_cycles()) <= (begin + d + margin) && !timer_info_.timer_works)
+		cpu_relax();
+
+	report(timer_info_.timer_works, "timer interrupt received");
+	report(timer_info_.timer_irq_set, "pending timer interrupt bit set in irq handler");
+	report(timer_info_.timer_irq_set && timer_info_.timer_irq_cleared,
+	       "pending timer interrupt bit cleared by setting timer to -1");
+
+	if (timer_info_.timer_works) {
+		duration = end - begin;
+		report(duration >= d && duration <= (d + margin), "timer delay honored");
+	}
+
+	if (timer_info_.timer_irq_count > 1)
+		report_fail("timer interrupt received multiple times");
+
+	if (csr_read(CSR_SIE) & IE_TIE) {
+		timer_info_ = (struct timer_info){ .mask_timer_irq = true };
+		begin = timer_get_cycles();
+		ret = __time_sbi_ecall(begin + d);
+
+		report(!ret.error, "set timer for mask irq test");
+		if (ret.error)
+			report_info("set timer for mask irq test failed with %ld\n", ret.error);
+
+		while ((end = timer_get_cycles()) <= (begin + d + margin)
+		       && !timer_info_.timer_works)
+			cpu_relax();
+
+		report(timer_info_.timer_works, "timer interrupt received for mask irq test");
+		report(timer_info_.timer_irq_set,
+		       "pending timer interrupt bit set in irq handler for mask irq test");
+		report(timer_info_.timer_irq_set && timer_info_.timer_irq_cleared,
+		       "pending timer interrupt bit cleared by masking timer irq");
+
+		if (timer_info_.timer_works) {
+			duration = end - begin;
+			report(duration >= d && duration <= (d + margin),
+			"timer delay honored for mask irq test");
+		}
+
+		if (timer_info_.timer_irq_count > 1)
+			report_fail("timer interrupt received multiple times for mask irq test");
+	} else {
+		report_skip("timer irq enable bit is not writable, skipping mask irq test");
+	}
+
+	local_irq_disable();
+	install_irq_handler(IRQ_S_TIMER, NULL);
+
+	report_prefix_pop();
+	report_prefix_pop();
+}
+
 int main(int argc, char **argv)
 {
 
@@ -122,6 +265,7 @@ int main(int argc, char **argv)
 
 	report_prefix_push("sbi");
 	check_base();
+	check_time();
 
 	return report_summary();
 }
-- 
2.43.0

Re: [kvm-unit-tests PATCH v5 5/5] riscv: sbi: Add test for timer extension

[Andrew Jones]

On Mon, Jul 29, 2024 at 12:50:22AM GMT, James Raphael Tiovalen wrote:
> Add a test for the set_timer function of the time extension. The test
> checks that:
> - The time extension is available
> - The installed timer interrupt handler is called
> - The timer interrupt is received within a reasonable time interval
> - The timer interrupt pending bit is cleared after the set_timer SBI
>   call is made
> - The timer interrupt can be cleared either by requesting a timer
>   interrupt infinitely far into the future or by masking the timer
>   interrupt
> 
> The timer interrupt delay can be set using the TIMER_DELAY environment
> variable in microseconds. The default delay value is 200 milliseconds.
> Since the interrupt can arrive a little later than the specified delay,
> allow some margin of error. This margin of error can be specified via
> the TIMER_MARGIN environment variable in microseconds. The default
> margin of error is 200 milliseconds.
> 
> Signed-off-by: James Raphael Tiovalen <jamestiotio@gmail.com>
> ---
>  lib/riscv/asm/csr.h   |   8 +++
>  lib/riscv/asm/sbi.h   |   5 ++
>  lib/riscv/asm/timer.h |  10 +++
>  riscv/sbi.c           | 144 ++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 167 insertions(+)
> 
> diff --git a/lib/riscv/asm/csr.h b/lib/riscv/asm/csr.h
> index a9b1bd42..24b333e0 100644
> --- a/lib/riscv/asm/csr.h
> +++ b/lib/riscv/asm/csr.h
> @@ -4,11 +4,15 @@
>  #include <linux/const.h>
>  
>  #define CSR_SSTATUS		0x100
> +#define CSR_SIE			0x104
>  #define CSR_STVEC		0x105
>  #define CSR_SSCRATCH		0x140
>  #define CSR_SEPC		0x141
>  #define CSR_SCAUSE		0x142
>  #define CSR_STVAL		0x143
> +#define CSR_SIP			0x144
> +#define CSR_STIMECMP		0x14d
> +#define CSR_STIMECMPH		0x15d
>  #define CSR_SATP		0x180
>  #define CSR_TIME		0xc01
>  
> @@ -47,6 +51,10 @@
>  #define IRQ_S_GEXT		12
>  #define IRQ_PMU_OVF		13
>  
> +#define IE_TIE			(_AC(0x1, UL) << IRQ_S_TIMER)
> +
> +#define IP_TIP			IE_TIE
> +
>  #ifndef __ASSEMBLY__
>  
>  #define csr_swap(csr, val)					\
> diff --git a/lib/riscv/asm/sbi.h b/lib/riscv/asm/sbi.h
> index 5e1a674a..73ab5438 100644
> --- a/lib/riscv/asm/sbi.h
> +++ b/lib/riscv/asm/sbi.h
> @@ -16,6 +16,7 @@
>  
>  enum sbi_ext_id {
>  	SBI_EXT_BASE = 0x10,
> +	SBI_EXT_TIME = 0x54494d45,
>  	SBI_EXT_HSM = 0x48534d,
>  	SBI_EXT_SRST = 0x53525354,
>  };
> @@ -37,6 +38,10 @@ enum sbi_ext_hsm_fid {
>  	SBI_EXT_HSM_HART_SUSPEND,
>  };
>  
> +enum sbi_ext_time_fid {
> +	SBI_EXT_TIME_SET_TIMER = 0,
> +};
> +
>  struct sbiret {
>  	long error;
>  	long value;
> diff --git a/lib/riscv/asm/timer.h b/lib/riscv/asm/timer.h
> index f7504f84..b3514d3f 100644
> --- a/lib/riscv/asm/timer.h
> +++ b/lib/riscv/asm/timer.h
> @@ -11,4 +11,14 @@ static inline uint64_t timer_get_cycles(void)
>  	return csr_read(CSR_TIME);
>  }
>  
> +static inline void timer_irq_enable(void)
> +{
> +	csr_set(CSR_SIE, IE_TIE);
> +}
> +
> +static inline void timer_irq_disable(void)
> +{
> +	csr_clear(CSR_SIE, IE_TIE);
> +}
> +
>  #endif /* _ASMRISCV_TIMER_H_ */
> diff --git a/riscv/sbi.c b/riscv/sbi.c
> index 762e9711..044258bb 100644
> --- a/riscv/sbi.c
> +++ b/riscv/sbi.c
> @@ -6,7 +6,25 @@
>   */
>  #include <libcflat.h>
>  #include <stdlib.h>
> +#include <limits.h>
> +#include <asm/barrier.h>
> +#include <asm/csr.h>
> +#include <asm/delay.h>
> +#include <asm/isa.h>
> +#include <asm/processor.h>
>  #include <asm/sbi.h>
> +#include <asm/smp.h>
> +#include <asm/timer.h>
> +
> +struct timer_info {
> +	bool timer_works;
> +	bool mask_timer_irq;
> +	bool timer_irq_set;
> +	bool timer_irq_cleared;
> +	unsigned long timer_irq_count;
> +};
> +
> +static struct timer_info timer_info_;

I'd rather call this just 'timer_info' than 'timer_info_'. I usually
prefer to use a different name than the struct for grepping purposes,
but for a static structure of a small file it doesn't really matter.

>  
>  static void help(void)
>  {
> @@ -19,6 +37,36 @@ static struct sbiret __base_sbi_ecall(int fid, unsigned long arg0)
>  	return sbi_ecall(SBI_EXT_BASE, fid, arg0, 0, 0, 0, 0, 0);
>  }
>  
> +static struct sbiret __time_sbi_ecall(unsigned long stime_value)
> +{
> +	return sbi_ecall(SBI_EXT_TIME, SBI_EXT_TIME_SET_TIMER, stime_value, 0, 0, 0, 0, 0);
> +}
> +
> +static bool timer_irq_pending(void)
> +{
> +	return csr_read(CSR_SIP) & IP_TIP;
> +}
> +
> +static void timer_irq_handler(struct pt_regs *regs)
> +{
> +	if (timer_info_.timer_irq_count < ULONG_MAX)
> +		++timer_info_.timer_irq_count;
> +
> +	timer_info_.timer_works = true;
> +	if (timer_irq_pending())
> +		timer_info_.timer_irq_set = true;
> +
> +	if (timer_info_.mask_timer_irq) {
> +		timer_irq_disable();
> +		__time_sbi_ecall(0);
> +	} else {
> +		__time_sbi_ecall(ULONG_MAX);
> +	}
> +
> +	if (!timer_irq_pending())
> +		timer_info_.timer_irq_cleared = true;
> +}
> +
>  static bool env_or_skip(const char *env)
>  {
>  	if (!getenv(env)) {
> @@ -112,6 +160,101 @@ static void check_base(void)
>  	report_prefix_pop();
>  }
>  
> +static void check_time(void)
> +{
> +	struct sbiret ret;
> +	unsigned long begin, end, duration;
> +	unsigned long d = getenv("TIMER_DELAY") ? strtol(getenv("TIMER_DELAY"), NULL, 0)
> +						: 200000;
> +	unsigned long margin = getenv("TIMER_MARGIN") ? strtol(getenv("TIMER_MARGIN"), NULL, 0)
> +						      : 200000;
> +
> +	d = usec_to_cycles(d);
> +	margin = usec_to_cycles(margin);
> +
> +	report_prefix_push("time");
> +
> +	if (!sbi_probe(SBI_EXT_TIME)) {
> +		report_skip("time extension not available");
> +		report_prefix_pop();
> +		return;
> +	}
> +
> +	report_prefix_push("set_timer");
> +
> +	install_irq_handler(IRQ_S_TIMER, timer_irq_handler);
> +	local_irq_enable();
> +	if (cpu_has_extension(smp_processor_id(), ISA_SSTC)) {
> +		csr_write(CSR_STIMECMP, ULONG_MAX);
> +#if __riscv_xlen == 32
> +		csr_write(CSR_STIMECMPH, ULONG_MAX);
> +#endif
> +	}
> +	timer_irq_enable();
> +
> +	begin = timer_get_cycles();
> +	ret = __time_sbi_ecall(begin + d);
> +
> +	report(!ret.error, "set timer");
> +	if (ret.error)
> +		report_info("set timer failed with %ld\n", ret.error);
> +
> +	report(!timer_irq_pending(), "pending timer interrupt bit cleared");
> +
> +	while ((end = timer_get_cycles()) <= (begin + d + margin) && !timer_info_.timer_works)
> +		cpu_relax();
> +
> +	report(timer_info_.timer_works, "timer interrupt received");
> +	report(timer_info_.timer_irq_set, "pending timer interrupt bit set in irq handler");
> +	report(timer_info_.timer_irq_set && timer_info_.timer_irq_cleared,
> +	       "pending timer interrupt bit cleared by setting timer to -1");
> +
> +	if (timer_info_.timer_works) {
> +		duration = end - begin;
> +		report(duration >= d && duration <= (d + margin), "timer delay honored");
> +	}
> +
> +	if (timer_info_.timer_irq_count > 1)
> +		report_fail("timer interrupt received multiple times");
> +
> +	if (csr_read(CSR_SIE) & IE_TIE) {
> +		timer_info_ = (struct timer_info){ .mask_timer_irq = true };
> +		begin = timer_get_cycles();
> +		ret = __time_sbi_ecall(begin + d);
> +
> +		report(!ret.error, "set timer for mask irq test");
> +		if (ret.error)
> +			report_info("set timer for mask irq test failed with %ld\n", ret.error);
> +
> +		while ((end = timer_get_cycles()) <= (begin + d + margin)
> +		       && !timer_info_.timer_works)
> +			cpu_relax();
> +
> +		report(timer_info_.timer_works, "timer interrupt received for mask irq test");
> +		report(timer_info_.timer_irq_set,
> +		       "pending timer interrupt bit set in irq handler for mask irq test");
> +		report(timer_info_.timer_irq_set && timer_info_.timer_irq_cleared,
> +		       "pending timer interrupt bit cleared by masking timer irq");
> +
> +		if (timer_info_.timer_works) {
> +			duration = end - begin;
> +			report(duration >= d && duration <= (d + margin),
> +			"timer delay honored for mask irq test");
> +		}
> +
> +		if (timer_info_.timer_irq_count > 1)
> +			report_fail("timer interrupt received multiple times for mask irq test");

nit: we could share all the code in the body of this if-statement with the
code above if we just create a function which takes a const char * which
would be NULL for the first invocation and "for mask irq test" for the
second.

> +	} else {
> +		report_skip("timer irq enable bit is not writable, skipping mask irq test");
> +	}
> +
> +	local_irq_disable();
> +	install_irq_handler(IRQ_S_TIMER, NULL);
> +
> +	report_prefix_pop();
> +	report_prefix_pop();
> +}
> +
>  int main(int argc, char **argv)
>  {
>  
> @@ -122,6 +265,7 @@ int main(int argc, char **argv)
>  
>  	report_prefix_push("sbi");
>  	check_base();
> +	check_time();
>  
>  	return report_summary();
>  }
> -- 
> 2.43.0
>

Reviewed-by: Andrew Jones <andrew.jones@linux.dev>

Thanks,
drew