Re: [PATCH v2 04/13] KVM: arm64: Refactor sys_regs.h, c for nVHE reuse

Hi Will,

On Thu, Jul 1, 2021 at 2:09 PM Will Deacon [off-list ref] wrote:

On Tue, Jun 15, 2021 at 02:39:41PM +0100, Fuad Tabba wrote:

quoted

Refactor sys_regs.h and sys_regs.c to make it easier to reuse
common code. It will be used in nVHE in a later patch.

No functional change intended.

Signed-off-by: Fuad Tabba <redacted>
---
 arch/arm64/kvm/sys_regs.c | 30 +-----------------------------
 arch/arm64/kvm/sys_regs.h | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 29 deletions(-)

[...]

quoted

diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
index 9d0621417c2a..b8e2a4dd830f 100644
--- a/arch/arm64/kvm/sys_regs.h
+++ b/arch/arm64/kvm/sys_regs.h

@@ -11,6 +11,12 @@
 #ifndef __ARM64_KVM_SYS_REGS_LOCAL_H__
 #define __ARM64_KVM_SYS_REGS_LOCAL_H__

+#include <linux/bsearch.h>
+
+#define reg_to_encoding(x)                                           \
+     sys_reg((u32)(x)->Op0, (u32)(x)->Op1,                           \
+             (u32)(x)->CRn, (u32)(x)->CRm, (u32)(x)->Op2)
+
 struct sys_reg_params {
      u8      Op0;
      u8      Op1;

@@ -21,6 +27,14 @@ struct sys_reg_params {
      bool    is_write;
 };

+#define esr_sys64_to_params(esr)                                               \
+     ((struct sys_reg_params){ .Op0 = ((esr) >> 20) & 3,                    \
+                               .Op1 = ((esr) >> 14) & 0x7,                  \
+                               .CRn = ((esr) >> 10) & 0xf,                  \
+                               .CRm = ((esr) >> 1) & 0xf,                   \
+                               .Op2 = ((esr) >> 17) & 0x7,                  \
+                               .is_write = !((esr)&1) })

Formatting has gone funny here (need spaces around the '&' in that last
entry).

Will fix this.

quoted

+
 struct sys_reg_desc {
      /* Sysreg string for debug */
      const char *name;

@@ -152,6 +166,24 @@ static inline int cmp_sys_reg(const struct sys_reg_desc *i1,
      return i1->Op2 - i2->Op2;
 }

+static inline int match_sys_reg(const void *key, const void *elt)
+{
+     const unsigned long pval = (unsigned long)key;
+     const struct sys_reg_desc *r = elt;
+
+     return pval - reg_to_encoding(r);
+}
+
+static inline const struct sys_reg_desc *
+find_reg(const struct sys_reg_params *params, const struct sys_reg_desc table[],
+      unsigned int num)
+{
+     unsigned long pval = reg_to_encoding(params);
+
+     return __inline_bsearch((void *)pval, table, num, sizeof(table[0]),
+                             match_sys_reg);

You don't mention why you change bsearch() to __inline_bsearch().

It's because of linking with nvhe. Rather than copy the bsearch code
for nvhe, I thought I'd use the inline version of bsearch. I'll update
the comment to explain that.

Thanks,
/fuad

Will

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