Re: [PATCH v3 05/15] KVM: arm64: Refactor sys_regs.h, c for nVHE reuse

Hi,

On Tue, Jul 20, 2021 at 2:38 PM Andrew Jones [off-list ref] wrote:

On Mon, Jul 19, 2021 at 05:03:36PM +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.

Note that the refactored code uses __inline_bsearch for find_reg
instead of bsearch to avoid copying the bsearch code for nVHE.

No functional change intended.

Signed-off-by: Fuad Tabba <tabba@google.com>
---
 arch/arm64/include/asm/sysreg.h |  3 +++
 arch/arm64/kvm/sys_regs.c       | 30 +-----------------------------
 arch/arm64/kvm/sys_regs.h       | 31 +++++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+), 29 deletions(-)

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 7b9c3acba684..326f49e7bd42 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h

@@ -1153,6 +1153,9 @@
 #define ICH_VTR_A3V_SHIFT    21
 #define ICH_VTR_A3V_MASK     (1 << ICH_VTR_A3V_SHIFT)

+/* Extract the feature specified from the feature id register. */
+#define FEATURE(x)   (GENMASK_ULL(x##_SHIFT + 3, x##_SHIFT))

I think the comment would be better as

 Create a mask for the feature bits of the specified feature.

I agree. I'll use this instead.

And, I think a more specific name than FEATURE would be better. Maybe
FEATURE_MASK or even ARM64_FEATURE_MASK ?

I think so too. ARM64_FEATURE_MASK is more descriptive than just FEATURE.

Thanks,
/fuad

quoted

+
 #ifdef __ASSEMBLY__

      .irp    num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 80a6e41cadad..1a939c464858 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c

@@ -44,10 +44,6 @@
  * 64bit interface.
  */

-#define reg_to_encoding(x)                                           \
-     sys_reg((u32)(x)->Op0, (u32)(x)->Op1,                           \
-             (u32)(x)->CRn, (u32)(x)->CRm, (u32)(x)->Op2)
-
 static bool read_from_write_only(struct kvm_vcpu *vcpu,
                               struct sys_reg_params *params,
                               const struct sys_reg_desc *r)

@@ -1026,8 +1022,6 @@ static bool access_arch_timer(struct kvm_vcpu *vcpu,
      return true;
 }

-#define FEATURE(x)   (GENMASK_ULL(x##_SHIFT + 3, x##_SHIFT))
-
 /* Read a sanitised cpufeature ID register by sys_reg_desc */
 static u64 read_id_reg(const struct kvm_vcpu *vcpu,
              struct sys_reg_desc const *r, bool raz)

@@ -2106,23 +2100,6 @@ static int check_sysreg_table(const struct sys_reg_desc *table, unsigned int n,
      return 0;
 }

-static 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 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 bsearch((void *)pval, table, num, sizeof(table[0]), match_sys_reg);
-}
-
 int kvm_handle_cp14_load_store(struct kvm_vcpu *vcpu)
 {
      kvm_inject_undefined(vcpu);

@@ -2365,13 +2342,8 @@ int kvm_handle_sys_reg(struct kvm_vcpu *vcpu)

      trace_kvm_handle_sys_reg(esr);

-     params.Op0 = (esr >> 20) & 3;
-     params.Op1 = (esr >> 14) & 0x7;
-     params.CRn = (esr >> 10) & 0xf;
-     params.CRm = (esr >> 1) & 0xf;
-     params.Op2 = (esr >> 17) & 0x7;
+     params = esr_sys64_to_params(esr);
      params.regval = vcpu_get_reg(vcpu, Rt);
-     params.is_write = !(esr & 1);

      ret = emulate_sys_reg(vcpu, &params);

diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
index 9d0621417c2a..cc0cc95a0280 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) })
+
 struct sys_reg_desc {
      /* Sysreg string for debug */
      const char *name;

@@ -152,6 +166,23 @@ 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);
+}
+
 const struct sys_reg_desc *find_reg_by_id(u64 id,
                                        struct sys_reg_params *params,
                                        const struct sys_reg_desc table[],
--

2.32.0.402.g57bb445576-goog

Otherwise

Reviewed-by: Andrew Jones <redacted>

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