[PATCH v3 6/7] target/i386/mshv: use the register page to set registers

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

Update mshv_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.

Signed-off-by: Doru Blânzeanu <dblanzeanu@linux.microsoft.com>
---
 include/system/mshv_int.h   |  2 +-
 target/i386/mshv/mshv-cpu.c | 70 ++++++++++++++++++++++++++-----------
 2 files changed, 50 insertions(+), 22 deletions(-)

diff --git a/include/system/mshv_int.h b/include/system/mshv_int.h
index a8a59ebf16..c2bc36ec60 100644
--- a/include/system/mshv_int.h
+++ b/include/system/mshv_int.h
@@ -86,7 +86,7 @@ int mshv_get_standard_regs(CPUState *cpu);
 int mshv_get_special_regs(CPUState *cpu);
 int mshv_run_vcpu(int vm_fd, CPUState *cpu, hv_message *msg, MshvVmExit *exit);
 void mshv_load_regs(CPUState *cpu);
-int mshv_store_regs(CPUState *cpu);
+void mshv_store_regs(CPUState *cpu);
 int mshv_set_generic_regs(const CPUState *cpu, const hv_register_assoc *assocs,
                           size_t n_regs);
 int mshv_arch_put_registers(const CPUState *cpu);
diff --git a/target/i386/mshv/mshv-cpu.c b/target/i386/mshv/mshv-cpu.c
index 500967b53e..a2bc29abd4 100644
--- a/target/i386/mshv/mshv-cpu.c
+++ b/target/i386/mshv/mshv-cpu.c
@@ -285,17 +285,56 @@ static int set_standard_regs(const CPUState *cpu)
     return 0;
 }
 
-int mshv_store_regs(CPUState *cpu)
+static void mshv_set_standard_regs_vp_page(CPUState *cpu)
 {
-    int ret;
+    X86CPU *x86cpu = X86_CPU(cpu);
+    CPUX86State *env = &x86cpu->env;
 
-    ret = set_standard_regs(cpu);
-    if (ret < 0) {
-        error_report("Failed to store standard registers");
-        return -1;
+    env->regs_page->rax = env->regs[R_EAX];
+    env->regs_page->rbx = env->regs[R_EBX];
+    env->regs_page->rcx = env->regs[R_ECX];
+    env->regs_page->rdx = env->regs[R_EDX];
+    env->regs_page->rsi = env->regs[R_ESI];
+    env->regs_page->rdi = env->regs[R_EDI];
+    env->regs_page->rsp = env->regs[R_ESP];
+    env->regs_page->rbp = env->regs[R_EBP];
+    env->regs_page->r8  = env->regs[R_R8];
+    env->regs_page->r9  = env->regs[R_R9];
+    env->regs_page->r10 = env->regs[R_R10];
+    env->regs_page->r11 = env->regs[R_R11];
+    env->regs_page->r12 = env->regs[R_R12];
+    env->regs_page->r13 = env->regs[R_R13];
+    env->regs_page->r14 = env->regs[R_R14];
+    env->regs_page->r15 = env->regs[R_R15];
+    env->regs_page->rip = env->eip;
+    lflags_to_rflags(env);
+    env->regs_page->rflags = env->eflags;
+
+    env->regs_page->dirty |= (1u << HV_X64_REGISTER_CLASS_GENERAL)
+                                | (1u << HV_X64_REGISTER_CLASS_IP)
+                                | (1u << HV_X64_REGISTER_CLASS_FLAGS);
+}
+
+void mshv_store_regs(CPUState *cpu)
+{
+    X86CPU *x86cpu = X86_CPU(cpu);
+    CPUX86State *env = &x86cpu->env;
+
+    /* 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();
+    }
+    if (env->regs_page->isvalid == 0) {
+        error_report(
+                "store regs: register page invalid for vcpu %d",
+                cpu->cpu_index);
+        abort();
     }
 
-    return 0;
+    mshv_set_standard_regs_vp_page(cpu);
 }
 
 static void populate_standard_regs(const hv_register_assoc *assocs,
@@ -1170,14 +1209,13 @@ 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 };
 
     mshv_load_regs(cpu);
@@ -1185,13 +1223,7 @@ static int emulate_instruction(CPUState *cpu,
     decode_instruction_stream(env, &decode, &stream);
     exec_instruction(env, &decode);
 
-    ret = mshv_store_regs(cpu);
-    if (ret < 0) {
-        error_report("failed to store registers");
-        return -1;
-    }
-
-    return 0;
+    mshv_store_regs(cpu);
 }
 
 static int handle_mmio(CPUState *cpu, const struct hyperv_message *msg,
@@ -1227,13 +1259,9 @@ 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