[PATCH v3 3/5] igvm: add support for initial register state load in native mode

[Gerd Hoffmann <kraxel@redhat.com>]

Add IgvmNativeVpContextX64 struct holding the register state (see igvm
spec), and the qigvm_x86_load_context() function to load the register
state.

Wire up using two new functions: qigvm_x86_set_vp_context() is called
from igvm file handling code and stores the boot processor context.
qigvm_x86_bsp_reset() is called from i386 target cpu reset code and
loads the context into the cpu registers.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 include/system/igvm.h |   2 +
 target/i386/cpu.h     |   3 +
 backends/igvm.c       |  30 +++++-----
 stubs/igvm.c          |   5 ++
 target/i386/cpu.c     |   4 ++
 target/i386/igvm.c    | 133 ++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 162 insertions(+), 15 deletions(-)

diff --git a/include/system/igvm.h b/include/system/igvm.h
index 3f72a40b8897..48ce20604259 100644
--- a/include/system/igvm.h
+++ b/include/system/igvm.h
@@ -23,5 +23,7 @@ int qigvm_process_file(IgvmCfg *igvm, ConfidentialGuestSupport *cgs,
 int qigvm_x86_get_mem_map_entry(int index,
                                 ConfidentialGuestMemoryMapEntry *entry,
                                 Error **errp);
+int qigvm_x86_set_vp_context(void *data, int index,
+                             Error **errp);
 
 #endif
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index ce948861a765..78d4b427c67a 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -2867,6 +2867,9 @@ void x86_cpu_dump_local_apic_state(CPUState *cs, int flags);
 
 #endif
 
+/* igvm.c */
+void qigvm_x86_bsp_reset(CPUX86State *env);
+
 /* cpu.c */
 bool cpu_is_bsp(X86CPU *cpu);
 
diff --git a/backends/igvm.c b/backends/igvm.c
index e949c81abb9a..ee5ee74c7a66 100644
--- a/backends/igvm.c
+++ b/backends/igvm.c
@@ -432,18 +432,6 @@ static int qigvm_directive_vp_context(QIgvm *ctx, const uint8_t *header_data,
         return 0;
     }
 
-    /*
-     * A confidential guest support object must be provided for setting
-     * a VP context.
-     */
-    if (!ctx->cgs) {
-        error_setg(
-            errp,
-            "A VP context is present in the IGVM file but is not supported "
-            "by the current system.");
-        return -1;
-    }
-
     data_handle = igvm_get_header_data(ctx->file, IGVM_HEADER_SECTION_DIRECTIVE,
                                        ctx->current_header_index);
     if (data_handle < 0) {
@@ -453,9 +441,21 @@ static int qigvm_directive_vp_context(QIgvm *ctx, const uint8_t *header_data,
     }
 
     data = (uint8_t *)igvm_get_buffer(ctx->file, data_handle);
-    result = ctx->cgsc->set_guest_state(
-        vp_context->gpa, data, igvm_get_buffer_size(ctx->file, data_handle),
-        CGS_PAGE_TYPE_VMSA, vp_context->vp_index, errp);
+
+    if (ctx->cgs) {
+        result = ctx->cgsc->set_guest_state(
+            vp_context->gpa, data, igvm_get_buffer_size(ctx->file, data_handle),
+            CGS_PAGE_TYPE_VMSA, vp_context->vp_index, errp);
+    } else if (target_arch() == SYS_EMU_TARGET_X86_64) {
+        result = qigvm_x86_set_vp_context(data, vp_context->vp_index, errp);
+    } else {
+        error_setg(
+            errp,
+            "A VP context is present in the IGVM file but is not supported "
+            "by the current system.");
+        result = -1;
+    }
+
     igvm_free_buffer(ctx->file, data_handle);
     if (result < 0) {
         return result;
diff --git a/stubs/igvm.c b/stubs/igvm.c
index c32058eb2a6e..17cd1e903e35 100644
--- a/stubs/igvm.c
+++ b/stubs/igvm.c
@@ -19,3 +19,8 @@ int qigvm_x86_get_mem_map_entry(int index,
 {
     return -1;
 }
+
+int qigvm_x86_set_vp_context(void *data, int index, Error **errp)
+{
+    return -1;
+}
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 455caff6b230..8dd5ac8020c2 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -8770,6 +8770,10 @@ static void x86_cpu_reset_hold(Object *obj, ResetType type)
 
     cs->halted = !cpu_is_bsp(cpu);
 
+    if (cpu_is_bsp(cpu)) {
+        qigvm_x86_bsp_reset(env);
+    }
+
     if (kvm_enabled()) {
         kvm_arch_reset_vcpu(cpu);
     }
diff --git a/target/i386/igvm.c b/target/i386/igvm.c
index 2ed6cd052c79..0921ec830508 100644
--- a/target/i386/igvm.c
+++ b/target/i386/igvm.c
@@ -11,9 +11,114 @@
 
 #include "qemu/osdep.h"
 
+#include "cpu.h"
 #include "hw/i386/e820_memory_layout.h"
 #include "system/igvm.h"
 
+struct IgvmNativeVpContextX64 {
+    uint64_t rax;
+    uint64_t rcx;
+    uint64_t rdx;
+    uint64_t rbx;
+    uint64_t rsp;
+    uint64_t rbp;
+    uint64_t rsi;
+    uint64_t rdi;
+    uint64_t r8;
+    uint64_t r9;
+    uint64_t r10;
+    uint64_t r11;
+    uint64_t r12;
+    uint64_t r13;
+    uint64_t r14;
+    uint64_t r15;
+    uint64_t rip;
+    uint64_t rflags;
+    uint64_t idtr_base;
+    uint16_t idtr_limit;
+    uint16_t reserved[2];
+    uint16_t gdtr_limit;
+    uint64_t gdtr_base;
+
+    uint16_t code_selector;
+    uint16_t code_attributes;
+    uint32_t code_base;
+    uint32_t code_limit;
+
+    uint16_t data_selector;
+    uint16_t data_attributes;
+    uint32_t data_base;
+    uint32_t data_limit;
+
+    uint64_t gs_base;
+    uint64_t cr0;
+    uint64_t cr3;
+    uint64_t cr4;
+    uint64_t efer;
+};
+
+#define FLAGS_TO_SEGCACHE(flags)                \
+    (((unsigned int)flags) << 8)
+
+static void qigvm_x86_load_context(struct IgvmNativeVpContextX64 *context, CPUX86State *env)
+{
+    cpu_load_efer(env, context->efer);
+    cpu_x86_update_cr4(env, context->cr4);
+    cpu_x86_update_cr0(env, context->cr0);
+    cpu_x86_update_cr3(env, context->cr3);
+
+    cpu_x86_load_seg_cache(
+        env, R_CS, context->code_selector,
+        context->code_base, context->code_limit,
+        FLAGS_TO_SEGCACHE(context->code_attributes));
+    cpu_x86_load_seg_cache(
+        env, R_DS, context->data_selector,
+        context->data_base, context->data_limit,
+        FLAGS_TO_SEGCACHE(context->data_attributes));
+    cpu_x86_load_seg_cache(
+        env, R_ES, context->data_selector,
+        context->data_base, context->data_limit,
+        FLAGS_TO_SEGCACHE(context->data_attributes));
+    cpu_x86_load_seg_cache(
+        env, R_FS, context->data_selector,
+        context->data_base, context->data_limit,
+        FLAGS_TO_SEGCACHE(context->data_attributes));
+    cpu_x86_load_seg_cache(
+        env, R_GS, context->data_selector,
+        context->data_base, context->data_limit,
+        FLAGS_TO_SEGCACHE(context->data_attributes));
+    cpu_x86_load_seg_cache(
+        env, R_SS, context->data_selector,
+        context->data_base, context->data_limit,
+        FLAGS_TO_SEGCACHE(context->data_attributes));
+
+    env->gdt.base = context->gdtr_base;
+    env->gdt.limit = context->gdtr_limit;
+    env->idt.base = context->idtr_base;
+    env->idt.limit = context->idtr_limit;
+
+    env->regs[R_EAX] = context->rax;
+    env->regs[R_ECX] = context->rcx;
+    env->regs[R_EDX] = context->rdx;
+    env->regs[R_EBX] = context->rbx;
+    env->regs[R_ESP] = context->rsp;
+    env->regs[R_EBP] = context->rbp;
+    env->regs[R_ESI] = context->rsi;
+    env->regs[R_EDI] = context->rdi;
+#ifdef TARGET_X86_64
+    env->regs[R_R8] = context->r8;
+    env->regs[R_R9] = context->r9;
+    env->regs[R_R10] = context->r10;
+    env->regs[R_R11] = context->r11;
+    env->regs[R_R12] = context->r12;
+    env->regs[R_R13] = context->r13;
+    env->regs[R_R14] = context->r14;
+    env->regs[R_R15] = context->r15;
+#endif
+    env->eip = context->rip;
+    env->eflags = context->rflags;
+}
+
 /*
  * convert e820 table into igvm memory map
  */
@@ -44,3 +149,31 @@ int qigvm_x86_get_mem_map_entry(int index,
     }
     return 0;
 }
+
+/*
+ * set initial cpu context
+ */
+static struct IgvmNativeVpContextX64 *bsp_context;
+
+int qigvm_x86_set_vp_context(void *data, int index, Error **errp)
+{
+    if (index != 0) {
+        error_setg(errp, "context can be set for BSP only");
+        return -1;
+    }
+
+    if (bsp_context == NULL) {
+        bsp_context = g_new0(struct IgvmNativeVpContextX64, 1);
+    }
+    memcpy(bsp_context, data, sizeof(struct IgvmNativeVpContextX64));
+    return 0;
+}
+
+void qigvm_x86_bsp_reset(CPUX86State *env)
+{
+    if (bsp_context == NULL) {
+        return;
+    }
+
+    qigvm_x86_load_context(bsp_context, env);
+}
-- 
2.51.0