On 03/11/2020 17:36, Andrew Jones wrote:
On Tue, Nov 03, 2020 at 05:03:15PM +0000, Alexandru Elisei wrote:
+}
+
+static inline bool system_supports_granule(size_t granule)
+{
+ u64 mmfr0 = get_id_aa64mmfr0_el1();
+
+ return ((granule == SZ_4K && ((mmfr0 >> 28) & 0xf) == 0) ||
+ (granule == SZ_64K && ((mmfr0 >> 24) & 0xf) == 0) ||
+ (granule == SZ_16K && ((mmfr0 >> 20) & 0xf) == 1));
+}
Or we can turn it into a switch statement and keep all the field defines. Either
way looks good to me (funny how tgran16 stands out).
Keeping the defines is probably a good idea. Whether the function uses
a switch or an expression like above doesn't matter to me much. Keeping
LOC down in the lib/ code is a goal of kvm-unit-tests, but so is
readabilty. If the switch looks better, then let's go that way.
I liked Drew's version in that it was very concise. The new version will
be much longer. If you think it's more readable I'll use that instead.
diff --git a/lib/arm64/asm/processor.h b/lib/arm64/asm/processor.h
index 02665b8..430ded3 100644
--- a/lib/arm64/asm/processor.h
+++ b/lib/arm64/asm/processor.h
@@ -117,5 +117,38 @@ static inline u64 get_ctr(void)
extern u32 dcache_line_size;
+static inline unsigned long get_id_aa64mmfr0_el1(void)
+{
+ return read_sysreg(id_aa64mmfr0_el1);
+}
+
+#define ID_AA64MMFR0_TGRAN4_SHIFT 28
+#define ID_AA64MMFR0_TGRAN64_SHIFT 24
+#define ID_AA64MMFR0_TGRAN16_SHIFT 20
+
+#define ID_AA64MMFR0_TGRAN4_SUPPORTED 0x0
+#define ID_AA64MMFR0_TGRAN64_SUPPORTED 0x0
+#define ID_AA64MMFR0_TGRAN16_SUPPORTED 0x1
+
+static inline bool system_supports_granule(size_t granule)
+{
+ u32 shift;
+ u32 val;
+ u64 mmfr0 = get_id_aa64mmfr0_el1();
+ if (granule == SZ_4K) {
+ shift = ID_AA64MMFR0_TGRAN4_SHIFT;
+ val = ID_AA64MMFR0_TGRAN4_SUPPORTED;
+ } else if (granule == SZ_16K) {
+ shift = ID_AA64MMFR0_TGRAN16_SHIFT;
+ val = ID_AA64MMFR0_TGRAN16_SUPPORTED;
+ } else {
+ assert(granule == SZ_64K);
+ shift = ID_AA64MMFR0_TGRAN64_SHIFT;
+ val = ID_AA64MMFR0_TGRAN64_SUPPORTED;
+ }
+
+ return ((mmfr0 >> shift) & 0xf) == val;
+}
+
#endif /* !__ASSEMBLY__ */
#endif /* _ASMARM64_PROCESSOR_H_ */
Thanks,
Nikos
Thanks,
drew
