qemu/memory-backup-Modify-the-VM-s-physical-bits-value-se.patch

From 65435e107fc8eee37c61a3a7d1adebd013ad466f Mon Sep 17 00:00:00 2001
From: Ming Yang <yangming73@huawei.com>
Date: Sat, 23 Mar 2024 16:18:03 +0800
Subject: [PATCH] memory: [backup] Modify the VM's physical bits value set
 policy.

backup code from qemu-6.2 to qemu-8.2
old info:
commit id :
a09c3928b33b0c53831bd9eeb56f8171c26057bc
messages:
target-i386: Modify the VM's physical bits value set policy.

To resolve the problem that a VM with large memory capacity fails
to be live migrated, determine whether the VM is a large memory
capacity based on the memory size (4 TB). If yes, set the bus width
of the VM address to 46 bits. If no, set the bus width to 42 bits.

Signed-off-by: Jinhua Cao <caojinhua1@huawei.com>
Signed-off-by: Jiajie Li <lijiajie11@huawei.com>

Signed-off-by: Ming Yang <yangming73@huawei.com>
---
 target/i386/cpu.c      | 20 +++++++++++++++++++-
 target/i386/cpu.h      |  6 ++++++
 target/i386/host-cpu.c | 13 +++++++------
 3 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index a66e5a357b..fc61a84b1e 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -7666,6 +7666,24 @@ static void x86_cpu_set_pc(CPUState *cs, vaddr value)
     cpu->env.eip = value;
 }
 
+
+/* At present, we check the vm is *LARGE* or not, i.e. whether
+ * the memory size is more than 4T or not.
+ */
+const uint64_t large_vm_mem_size = 0x40000000000UL;
+void x86_cpu_adjuest_by_ram_size(ram_addr_t ram_size, X86CPU *cpu)
+{
+    /* If there is not a large vm, we set the phys_bits to 42 bits,
+     * otherwise, we increase the phys_bits to 46 bits.
+     */
+    if (ram_size < large_vm_mem_size) {
+        cpu->phys_bits = DEFAULT_VM_CPU_PHYS_BITS;
+    } else {
+        cpu->phys_bits = LARGE_VM_CPU_PHYS_BITS;
+        cpu->fill_mtrr_mask = true;
+    }
+}
+
 static vaddr x86_cpu_get_pc(CPUState *cs)
 {
     X86CPU *cpu = X86_CPU(cs);
@@ -7868,7 +7886,7 @@ static Property x86_cpu_properties[] = {
     DEFINE_PROP_UINT32("phys-bits", X86CPU, phys_bits, 0),
     DEFINE_PROP_BOOL("host-phys-bits", X86CPU, host_phys_bits, false),
     DEFINE_PROP_UINT8("host-phys-bits-limit", X86CPU, host_phys_bits_limit, 0),
-    DEFINE_PROP_BOOL("fill-mtrr-mask", X86CPU, fill_mtrr_mask, true),
+    DEFINE_PROP_BOOL("fill-mtrr-mask", X86CPU, fill_mtrr_mask, false),
     DEFINE_PROP_UINT32("level-func7", X86CPU, env.cpuid_level_func7,
                        UINT32_MAX),
     DEFINE_PROP_UINT32("level", X86CPU, env.cpuid_level, UINT32_MAX),
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index ef987f344c..6993552cd9 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -24,6 +24,7 @@
 #include "cpu-qom.h"
 #include "kvm/hyperv-proto.h"
 #include "exec/cpu-defs.h"
+#include "exec/cpu-common.h"
 #include "qapi/qapi-types-common.h"
 #include "qemu/cpu-float.h"
 #include "qemu/timer.h"
@@ -2081,6 +2082,11 @@ struct X86CPUClass {
 extern const VMStateDescription vmstate_x86_cpu;
 #endif
 
+#define DEFAULT_VM_CPU_PHYS_BITS 42
+#define LARGE_VM_CPU_PHYS_BITS 46
+
+void x86_cpu_adjuest_by_ram_size(ram_addr_t ram_size, X86CPU *cpu);
+
 int x86_cpu_pending_interrupt(CPUState *cs, int interrupt_request);
 
 int x86_cpu_write_elf64_note(WriteCoreDumpFunction f, CPUState *cpu,
diff --git a/target/i386/host-cpu.c b/target/i386/host-cpu.c
index 92ecb7254b..07738bf857 100644
--- a/target/i386/host-cpu.c
+++ b/target/i386/host-cpu.c
@@ -13,6 +13,7 @@
 #include "qapi/error.h"
 #include "qemu/error-report.h"
 #include "sysemu/sysemu.h"
+#include "hw/boards.h"
 
 /* Note: Only safe for use on x86(-64) hosts */
 static uint32_t host_cpu_phys_bits(void)
@@ -57,14 +58,14 @@ static uint32_t host_cpu_adjust_phys_bits(X86CPU *cpu)
     uint32_t phys_bits = cpu->phys_bits;
     static bool warned;
 
-    /*
-     * Print a warning if the user set it to a value that's not the
-     * host value.
-     */
-    if (phys_bits != host_phys_bits && phys_bits != 0 &&
+    /* adjust x86 cpu phys_bits according to ram_size. */
+    x86_cpu_adjuest_by_ram_size(current_machine->ram_size, cpu);
+
+    /* Print a warning if the host value less than the user set. */
+    if (phys_bits > host_phys_bits && phys_bits != 0 &&
         !warned) {
         warn_report("Host physical bits (%u)"
-                    " does not match phys-bits property (%u)",
+                    " less than phys-bits property (%u)",
                     host_phys_bits, phys_bits);
         warned = true;
     }
-- 
2.27.0