Refine platform features control

Allow a platform to report its supported features in more details.
The new features defined are:
* SBI_PLATFORM_HAS_PMP
* SBI_PLATFORM_HAS_SCOUNTEREN
* SBI_PLATFORM_HAS_MCOUNTEREN

In addition, define the macro SBI_PLATFORM_DEFAULT_FEATURES as the set
of features that are generally expected to be supported by a Linux
capable platform.

Operations touching the features controlled with these falgs are not
executed if the platform does not set the corresponding feature flags.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>

include/sbi/sbi_hart.h

@@ -16,7 +16,7 @@ struct sbi_scratch;
 
 int sbi_hart_init(struct sbi_scratch *scratch, u32 hartid);
 
-void sbi_hart_pmp_dump(void);
+void sbi_hart_pmp_dump(struct sbi_scratch *scratch);
 
 void __attribute__((noreturn)) sbi_hart_hang(void);
 

include/sbi/sbi_platform.h

@@ -13,10 +13,19 @@
 #include <sbi/sbi_scratch.h>
 
 enum sbi_platform_features {
-	SBI_PLATFORM_HAS_MMIO_TIMER_VALUE = (1 << 0),
-	SBI_PLATFORM_HAS_HART_HOTPLUG = (1 << 1),
+	SBI_PLATFORM_HAS_MMIO_TIMER_VALUE	= (1 << 0),
+	SBI_PLATFORM_HAS_HART_HOTPLUG		= (1 << 1),
+	SBI_PLATFORM_HAS_PMP			= (1 << 2),
+	SBI_PLATFORM_HAS_SCOUNTEREN		= (1 << 3),
+	SBI_PLATFORM_HAS_MCOUNTEREN		= (1 << 4),
 };
 
+#define SBI_PLATFORM_DEFAULT_FEATURES	\
+	(SBI_PLATFORM_HAS_MMIO_TIMER_VALUE | \
+	 SBI_PLATFORM_HAS_PMP | \
+	 SBI_PLATFORM_HAS_SCOUNTEREN | \
+	 SBI_PLATFORM_HAS_MCOUNTEREN)
+
 struct sbi_platform {
 	char name[64];
 	u64 features;
@@ -48,17 +57,20 @@ struct sbi_platform {
 	int (*system_shutdown)(u32 type);
 } __attribute__((packed));
 
-#define sbi_platform_ptr(__s)			\
-((struct sbi_platform *)((__s)->platform_addr))
-
-#define sbi_platform_thishart_ptr()			\
-((struct sbi_platform *)(sbi_scratch_thishart_ptr()->platform_addr))
-
+#define sbi_platform_ptr(__s)	\
+	((struct sbi_platform *)((__s)->platform_addr))
+#define sbi_platform_thishart_ptr()	\
+	((struct sbi_platform *)(sbi_scratch_thishart_ptr()->platform_addr))
 #define sbi_platform_has_mmio_timer_value(__p)	\
-((__p)->features & SBI_PLATFORM_HAS_MMIO_TIMER_VALUE)
-
+	((__p)->features & SBI_PLATFORM_HAS_MMIO_TIMER_VALUE)
 #define sbi_platform_has_hart_hotplug(__p)	\
-((__p)->features & SBI_PLATFORM_HAS_HART_HOTPLUG)
+	((__p)->features & SBI_PLATFORM_HAS_HART_HOTPLUG)
+#define sbi_platform_has_pmp(__p)	\
+	((__p)->features & SBI_PLATFORM_HAS_PMP)
+#define sbi_platform_has_scounteren(__p)	\
+	((__p)->features & SBI_PLATFORM_HAS_SCOUNTEREN)
+#define sbi_platform_has_mcounteren(__p)	\
+	((__p)->features & SBI_PLATFORM_HAS_MCOUNTEREN)
 
 static inline const char *sbi_platform_name(struct sbi_platform *plat)
 {

lib/sbi_hart.c

@@ -17,16 +17,20 @@
 #include <sbi/sbi_hart.h>
 #include <sbi/sbi_platform.h>
 
-static int mstatus_init(u32 hartid)
+static void mstatus_init(struct sbi_scratch *scratch, u32 hartid)
 {
+	struct sbi_platform *plat = sbi_platform_ptr(scratch);
+
 	/* Enable FPU */
 	if (misa_extension('D') || misa_extension('F'))
 		csr_write(mstatus, MSTATUS_FS);
 
 	/* Enable user/supervisor use of perf counters */
-	if (misa_extension('S'))
+	if (misa_extension('S') &&
+	     sbi_platform_has_scounteren(plat))
 		csr_write(scounteren, -1);
-	csr_write(mcounteren, -1);
+	if (sbi_platform_has_mcounteren(plat))
+		csr_write(mcounteren, -1);
 
 	/* Disable all interrupts */
 	csr_write(mie, 0);
@@ -34,8 +38,6 @@ static int mstatus_init(u32 hartid)
 	/* Disable S-mode paging */
 	if (misa_extension('S'))
 		csr_write(sptbr, 0);
-
-	return 0;
 }
 
 #ifdef __riscv_flen
@@ -111,10 +113,14 @@ unsigned long log2roundup(unsigned long x)
 	return ret;
 }
 
-void sbi_hart_pmp_dump(void)
+void sbi_hart_pmp_dump(struct sbi_scratch *scratch)
 {
-	unsigned int i;
+	struct sbi_platform *plat = sbi_platform_ptr(scratch);
 	unsigned long prot, addr, size, l2l;
+	unsigned int i;
+
+	if (!sbi_platform_has_pmp(plat))
+		return;
 
 	for (i = 0; i < PMP_COUNT; i++) {
 		pmp_get(i, &prot, &addr, &l2l);
@@ -149,6 +155,9 @@ static int pmp_init(struct sbi_scratch *scratch, u32 hartid)
 	ulong prot, addr, log2size;
 	struct sbi_platform *plat = sbi_platform_ptr(scratch);
 
+	if (!sbi_platform_has_pmp(plat))
+		return 0;
+
 	fw_size_log2 = log2roundup(scratch->fw_size);
 	fw_start = scratch->fw_start & ~((1UL << fw_size_log2) - 1UL);
 
@@ -172,9 +181,7 @@ int sbi_hart_init(struct sbi_scratch *scratch, u32 hartid)
 {
 	int rc;
 
-	rc = mstatus_init(hartid);
-	if (rc)
-		return rc;
+	mstatus_init(scratch, hartid);
 
 	rc = fp_init(hartid);
 	if (rc)

lib/sbi_init.c

@@ -91,7 +91,7 @@ static void __attribute__((noreturn)) init_coldboot(struct sbi_scratch *scratch,
 		   sbi_ecall_version_major(), sbi_ecall_version_minor());
 	sbi_printf("\n");
 
-	sbi_hart_pmp_dump();
+	sbi_hart_pmp_dump(scratch);
 
 	sbi_hart_mark_available(hartid);
 

platform/qemu/sifive_u/platform.c

@@ -88,7 +88,7 @@ static int sifive_u_system_down(u32 type)
 
 struct sbi_platform platform = {
 	.name = STRINGIFY(PLAT_NAME),
-	.features = SBI_PLATFORM_HAS_MMIO_TIMER_VALUE,
+	.features = SBI_PLATFORM_DEFAULT_FEATURES,
 	.hart_count = PLAT_HART_COUNT,
 	.hart_stack_size = PLAT_HART_STACK_SIZE,
 	.pmp_region_count = sifive_u_pmp_region_count,

platform/qemu/virt/platform.c

@@ -86,7 +86,7 @@ static int virt_system_down(u32 type)
 
 struct sbi_platform platform = {
 	.name = STRINGIFY(PLAT_NAME),
-	.features = SBI_PLATFORM_HAS_MMIO_TIMER_VALUE,
+	.features = SBI_PLATFORM_DEFAULT_FEATURES,
 	.hart_count = PLAT_HART_COUNT,
 	.hart_stack_size = PLAT_HART_STACK_SIZE,
 	.pmp_region_count = virt_pmp_region_count,

platform/sifive/hifive_u540/platform.c

@@ -105,7 +105,7 @@ static int sifive_u_system_down(u32 type)
 
 struct sbi_platform platform = {
 	.name = STRINGIFY(PLAT_NAME),
-	.features = SBI_PLATFORM_HAS_MMIO_TIMER_VALUE,
+	.features = SBI_PLATFORM_DEFAULT_FEATURES;
 	.hart_count = PLAT_HART_COUNT,
 	.hart_stack_size = PLAT_HART_STACK_SIZE,
 	.pmp_region_count = sifive_u_pmp_region_count,