[PATCH 4/5] target/i386/mshv: remove fallback for register page set registers

["Doru Blânzeanu" <dblanzeanu@linux.microsoft.com>]

Update `store_regs` to use the register page when it is mmapped and
valid to set registers.
Remove the ioctl based register retrieval and fail in case the register
page is not correctly set or valid.

Fixes: 80c7f8e9cd
Signed-off-by: Doru Blânzeanu <dblanzeanu@linux.microsoft.com>
---
 target/i386/mshv/mshv-cpu.c | 48 +++++++++++++------------------------
 1 file changed, 17 insertions(+), 31 deletions(-)

diff --git a/target/i386/mshv/mshv-cpu.c b/target/i386/mshv/mshv-cpu.c
index 9ec5c19c67..8a59a0b40e 100644
--- a/target/i386/mshv/mshv-cpu.c
+++ b/target/i386/mshv/mshv-cpu.c
@@ -448,7 +448,7 @@ static int set_standard_regs(const CPUState *cpu)
     return 0;
 }
 
-static void mshv_set_standard_regs_vp_page(CPUState *cpu)
+static void set_standard_regs_vp_page(CPUState *cpu)
 {
     X86CPU *x86cpu = X86_CPU(cpu);
     CPUX86State *env = &x86cpu->env;
@@ -478,29 +478,26 @@ static void mshv_set_standard_regs_vp_page(CPUState *cpu)
                                 | (1u << HV_X64_REGISTER_CLASS_FLAGS);
 }
 
-static int store_regs(CPUState *cpu)
+static void store_regs(CPUState *cpu)
 {
     X86CPU *x86cpu = X86_CPU(cpu);
     CPUX86State *env = &x86cpu->env;
-    int ret;
 
-    /* Use register vp page to optimize registers access */
-    if (env->regs_page && env->regs_page->isvalid != 0) {
-        mshv_set_standard_regs_vp_page(cpu);
-    } else {
-        ret = set_standard_regs(cpu);
-        if (ret < 0) {
-            return ret;
-        }
+    /* Check register page pointer and abort if in unexpected state */
+    if (!env->regs_page) {
+        error_report(
+                "store regs: register page not set for vcpu %d",
+                cpu->cpu_index);
+        abort();
     }
-
-    ret = set_special_regs(cpu);
-    if (ret < 0) {
-        error_report("Failed to store speical registers");
-        return ret;
+    if (env->regs_page->isvalid == 0) {
+        error_report(
+                "store regs: register page invalid for vcpu %d",
+                cpu->cpu_index);
+        abort();
     }
 
-    return 0;
+    set_standard_regs_vp_page(cpu);
 }
 
 static void populate_standard_regs(const hv_register_assoc *assocs,
@@ -1518,14 +1515,13 @@ static int set_memory_info(const struct hyperv_message *msg,
     return 0;
 }
 
-static int emulate_instruction(CPUState *cpu,
+static void emulate_instruction(CPUState *cpu,
                                const uint8_t *insn_bytes, size_t insn_len,
                                uint64_t gva, uint64_t gpa)
 {
     X86CPU *x86_cpu = X86_CPU(cpu);
     CPUX86State *env = &x86_cpu->env;
     struct x86_decode decode = { 0 };
-    int ret;
     x86_insn_stream stream = { .bytes = insn_bytes, .len = insn_len };
 
     load_regs(cpu);
@@ -1533,13 +1529,7 @@ static int emulate_instruction(CPUState *cpu,
     decode_instruction_stream(env, &decode, &stream);
     exec_instruction(env, &decode);
 
-    ret = store_regs(cpu);
-    if (ret < 0) {
-        error_report("failed to store registers");
-        return -1;
-    }
-
-    return 0;
+    store_regs(cpu);
 }
 
 static int handle_mmio(CPUState *cpu, const struct hyperv_message *msg,
@@ -1575,13 +1565,9 @@ static int handle_mmio(CPUState *cpu, const struct hyperv_message *msg,
 
     instruction_bytes = info.instruction_bytes;
 
-    ret = emulate_instruction(cpu, instruction_bytes, insn_len,
+    emulate_instruction(cpu, instruction_bytes, insn_len,
                               info.guest_virtual_address,
                               info.guest_physical_address);
-    if (ret < 0) {
-        error_report("failed to emulate mmio");
-        return -1;
-    }
 
     *exit_reason = MshvVmExitIgnore;
 
-- 
2.53.0