[PULL 11/19] target/i386: emulate: indirect access to CRs

[Paolo Bonzini <pbonzini@redhat.com>]

From: Mohamed Mediouni <mohamed@unpredictable.fr>

Prepare to have on-demand fetch of registers from the backend during
faults.

For x86_64 macOS, copy the function there too.

Signed-off-by: Mohamed Mediouni <mohamed@unpredictable.fr>
Link: https://lore.kernel.org/r/20260324151323.74473-9-mohamed@unpredictable.fr
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/emulate/x86_emu.h     |  3 +++
 target/i386/emulate/x86_helpers.c | 27 ++++++++++++++++-----------
 target/i386/emulate/x86_mmu.c     |  8 ++------
 target/i386/hvf/x86.c             | 11 +++++++++++
 4 files changed, 32 insertions(+), 17 deletions(-)

diff --git a/target/i386/emulate/x86_emu.h b/target/i386/emulate/x86_emu.h
index 4ed970bd536..a8d4c93098d 100644
--- a/target/i386/emulate/x86_emu.h
+++ b/target/i386/emulate/x86_emu.h
@@ -28,6 +28,7 @@ struct x86_emul_ops {
     MMUTranslateResult (*mmu_gva_to_gpa) (CPUState *cpu, target_ulong gva, uint64_t *gpa, MMUTranslateFlags flags);
     void (*read_segment_descriptor)(CPUState *cpu, struct x86_segment_descriptor *desc,
                                     enum X86Seg seg);
+    target_ulong (*read_cr) (CPUState *cpu, int cr);
     void (*handle_io)(CPUState *cpu, uint16_t port, void *data, int direction,
                       int size, int count);
     void (*simulate_rdmsr)(CPUState *cs);
@@ -45,6 +46,8 @@ void x86_emul_raise_exception(CPUX86State *env, int exception_index, int error_c
 
 target_ulong read_reg(CPUX86State *env, int reg, int size);
 void write_reg(CPUX86State *env, int reg, target_ulong val, int size);
+target_ulong x86_read_cr(CPUState *cpu, int cr);
+
 target_ulong read_val_from_reg(void *reg_ptr, int size);
 void write_val_to_reg(void *reg_ptr, target_ulong val, int size);
 bool write_val_ext(CPUX86State *env, struct x86_decode_op *decode, target_ulong val, int size);
diff --git a/target/i386/emulate/x86_helpers.c b/target/i386/emulate/x86_helpers.c
index ebbf40f2b05..c817015ef92 100644
--- a/target/i386/emulate/x86_helpers.c
+++ b/target/i386/emulate/x86_helpers.c
@@ -206,15 +206,26 @@ bool x86_read_call_gate(CPUState *cpu, struct x86_call_gate *idt_desc,
     return true;
 }
 
-bool x86_is_protected(CPUState *cpu)
+target_ulong x86_read_cr(CPUState *cpu, int cr)
 {
     X86CPU *x86_cpu = X86_CPU(cpu);
     CPUX86State *env = &x86_cpu->env;
-    uint64_t cr0 = env->cr[0];
+
+    if (emul_ops->read_cr) {
+        return emul_ops->read_cr(cpu, cr);
+    }
+    return env->cr[cr];
+}
+
+bool x86_is_protected(CPUState *cpu)
+{
+    uint64_t cr0;
+
     if (emul_ops->is_protected_mode) {
         return emul_ops->is_protected_mode(cpu);
     }
 
+    cr0 = x86_read_cr(cpu, 0);
     return cr0 & CR0_PE_MASK;
 }
 
@@ -245,9 +256,7 @@ bool x86_is_long_mode(CPUState *cpu)
 
 bool x86_is_la57(CPUState *cpu)
 {
-    X86CPU *x86_cpu = X86_CPU(cpu);
-    CPUX86State *env = &x86_cpu->env;
-    uint64_t is_la57 = env->cr[4] & CR4_LA57_MASK;
+    uint64_t is_la57 = x86_read_cr(cpu, 4) & CR4_LA57_MASK;
     return is_la57;
 }
 
@@ -259,18 +268,14 @@ bool x86_is_long64_mode(CPUState *cpu)
 
 bool x86_is_paging_mode(CPUState *cpu)
 {
-    X86CPU *x86_cpu = X86_CPU(cpu);
-    CPUX86State *env = &x86_cpu->env;
-    uint64_t cr0 = env->cr[0];
+    uint64_t cr0 = x86_read_cr(cpu, 0);
 
     return cr0 & CR0_PG_MASK;
 }
 
 bool x86_is_pae_enabled(CPUState *cpu)
 {
-    X86CPU *x86_cpu = X86_CPU(cpu);
-    CPUX86State *env = &x86_cpu->env;
-    uint64_t cr4 = env->cr[4];
+    uint64_t cr4 = x86_read_cr(cpu, 4);
 
     return cr4 & CR4_PAE_MASK;
 }
diff --git a/target/i386/emulate/x86_mmu.c b/target/i386/emulate/x86_mmu.c
index 670939acdba..ba0ebe4268d 100644
--- a/target/i386/emulate/x86_mmu.c
+++ b/target/i386/emulate/x86_mmu.c
@@ -114,8 +114,6 @@ static bool get_pt_entry(CPUState *cpu, struct gpt_translation *pt,
 static MMUTranslateResult test_pt_entry(CPUState *cpu, struct gpt_translation *pt,
                           int level, int *largeness, bool pae, MMUTranslateFlags flags)
 {
-    X86CPU *x86_cpu = X86_CPU(cpu);
-    CPUX86State *env = &x86_cpu->env;
     uint64_t pte = pt->pte[level];
 
     if (!pte_present(pte)) {
@@ -130,7 +128,7 @@ static MMUTranslateResult test_pt_entry(CPUState *cpu, struct gpt_translation *p
         *largeness = level;
     }
 
-    uint32_t cr0 = env->cr[0];
+    uint32_t cr0 = x86_read_cr(cpu, 0);
     /* check protection */
     if (cr0 & CR0_WP_MASK) {
         if (mmu_validate_write(flags) && !pte_write_access(pte)) {
@@ -184,11 +182,9 @@ static inline uint64_t large_page_gpa(struct gpt_translation *pt, bool pae,
 static MMUTranslateResult walk_gpt(CPUState *cpu, target_ulong addr, MMUTranslateFlags flags,
                      struct gpt_translation *pt, bool pae)
 {
-    X86CPU *x86_cpu = X86_CPU(cpu);
-    CPUX86State *env = &x86_cpu->env;
     int top_level, level;
     int largeness = 0;
-    target_ulong cr3 = env->cr[3];
+    target_ulong cr3 = x86_read_cr(cpu, 3);
     uint64_t page_mask = pae ? PAE_PTE_PAGE_MASK : LEGACY_PTE_PAGE_MASK;
     MMUTranslateResult res;
     
diff --git a/target/i386/hvf/x86.c b/target/i386/hvf/x86.c
index 7fe710aca3b..bae2f30fa28 100644
--- a/target/i386/hvf/x86.c
+++ b/target/i386/hvf/x86.c
@@ -143,6 +143,17 @@ bool x86_is_la57(CPUState *cpu)
     return false;
 }
 
+target_ulong x86_read_cr(CPUState *cpu, int cr)
+{
+    X86CPU *x86_cpu = X86_CPU(cpu);
+    CPUX86State *env = &x86_cpu->env;
+
+    if (emul_ops->read_cr) {
+        return emul_ops->read_cr(cpu, cr);
+    }
+    return env->cr[cr];
+}
+
 bool x86_is_long64_mode(CPUState *cpu)
 {
     struct vmx_segment desc;
-- 
2.53.0