[PATCH v3 4/7] target/i386/mshv: hv_vp_register_page setup for the vcpu

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

When the vcpu is created, call mmap to configure access to the register page.
In case the call to mmap fails, we log an error and abort to signal
there is something wrong with the system.
Check the register page version and compare with the expected version and
abort in case of a mismatch.

Update CPUArchState to store a pointer to the mmapped hv_vp_register_page.

Signed-off-by: Doru Blânzeanu <dblanzeanu@linux.microsoft.com>
---
 target/i386/cpu.h           |  4 ++++
 target/i386/mshv/mshv-cpu.c | 24 ++++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index bdd4fff89d..d772b4c4cc 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -2214,6 +2214,10 @@ typedef struct CPUArchState {
     struct {} end_reset_fields;
 
     /* Fields after this point are preserved across CPU reset. */
+#ifdef CONFIG_MSHV
+    /* Shared register page */
+    struct hv_vp_register_page *regs_page;
+#endif
 
     /* processor features (e.g. for CPUID insn) */
     /* Minimum cpuid leaf 7 value */
diff --git a/target/i386/mshv/mshv-cpu.c b/target/i386/mshv/mshv-cpu.c
index 9defd05db6..45dc6e6331 100644
--- a/target/i386/mshv/mshv-cpu.c
+++ b/target/i386/mshv/mshv-cpu.c
@@ -1587,6 +1587,7 @@ void mshv_arch_init_vcpu(CPUState *cpu)
     CPUX86State *env = &x86_cpu->env;
     AccelCPUState *state = cpu->accel;
     size_t page = HV_HYP_PAGE_SIZE;
+    void *regs_page;
     void *mem = qemu_memalign(page, 2 * page);
 
     /* sanity check, to make sure we don't overflow the page */
@@ -1595,6 +1596,24 @@ void mshv_arch_init_vcpu(CPUState *cpu)
                       + sizeof(hv_input_get_vp_registers)
                       > HV_HYP_PAGE_SIZE));
 
+
+    /* mmap the registers page */
+    regs_page = mmap(NULL, page, PROT_READ | PROT_WRITE,
+                    MAP_SHARED, mshv_vcpufd(cpu),
+                    MSHV_VP_MMAP_OFFSET_REGISTERS * page);
+    if (regs_page == MAP_FAILED) {
+        /* This shouldn't fail, so we treat it as a fatal error */
+        error_report("register page mmap failed: %s", strerror(errno));
+        abort();
+    }
+    env->regs_page = (struct hv_vp_register_page *) regs_page;
+
+    if (env->regs_page->version != HV_VP_REGISTER_PAGE_VERSION_1) {
+        error_report("register page version mismatch: got %u, expected %u",
+                     env->regs_page->version, HV_VP_REGISTER_PAGE_VERSION_1);
+        abort();
+    }
+
     state->hvcall_args.base = mem;
     state->hvcall_args.input_page = mem;
     state->hvcall_args.output_page = (uint8_t *)mem + page;
@@ -1608,6 +1627,11 @@ void mshv_arch_destroy_vcpu(CPUState *cpu)
     CPUX86State *env = &x86_cpu->env;
     AccelCPUState *state = cpu->accel;
 
+    /* Unmap the register page */
+    if (env->regs_page) {
+        munmap(env->regs_page, HV_HYP_PAGE_SIZE);
+        env->regs_page = NULL;
+    }
     g_free(state->hvcall_args.base);
     state->hvcall_args = (MshvHvCallArgs){0};
     g_clear_pointer(&env->emu_mmio_buf, g_free);
-- 
2.53.0