qemu/backends-VirtCCA-cvm_gpa_start-supports-both-1GB-and.patch

From bc08940ad3c75da49e05c596f79e9e0164573709 Mon Sep 17 00:00:00 2001
From: gongchangsui <gongchangsui@outlook.com>
Date: Mon, 17 Mar 2025 02:56:40 -0400
Subject: [PATCH] backends: VirtCCA: cvm_gpa_start supports both 1GB and 3GB

For TMM versions 2.1 and above, `cvm_gpa_start` is 1GB, while for
versions prior to 2.1, `cvm_gpa_start` is 3GB. Shared huge page memory
supports both `cvm_gpa_start` values.

Signed-off-by: gongchangsui <gongchangsui@outlook.com>
---
 backends/hostmem-file.c | 17 ++++++++++++++---
 hw/arm/virt.c           |  1 +
 hw/core/numa.c          |  2 +-
 include/exec/memory.h   | 11 +++++++----
 4 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c
index 891fe4ac4a..ce63a372a3 100644
--- a/backends/hostmem-file.c
+++ b/backends/hostmem-file.c
@@ -27,6 +27,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(HostMemoryBackendFile, MEMORY_BACKEND_FILE)
 
 bool virtcca_shared_hugepage_mapped = false;
 uint64_t virtcca_cvm_ram_size = 0;
+uint64_t virtcca_cvm_gpa_start = 0;
 
 struct HostMemoryBackendFile {
     HostMemoryBackend parent_obj;
@@ -101,8 +102,16 @@ virtcca_shared_backend_memory_alloc(char *mem_path, uint32_t ram_flags, Error **
         error_report("parse virtcca share memory path failed");
         exit(1);
     }
-    if (virtcca_cvm_ram_size >= VIRTCCA_SHARED_HUGEPAGE_MAX_SIZE) {
-        size = VIRTCCA_SHARED_HUGEPAGE_MAX_SIZE;
+
+    /*
+     * 1) CVM_GPA_START = 3GB --> fix size = 1GB
+     * 2) CVM_GPA_START = 1GB && ram_size >= 3GB --> size = 3GB
+     * 3) CVM_GPA_START = 1GB && ram_size < 3GB  --> size = ram_size
+     */
+    if (virtcca_cvm_gpa_start != DEFAULT_VM_GPA_START) {
+        size = VIRTCCA_SHARED_HUGEPAGE_ADDR_LIMIT - virtcca_cvm_gpa_start;
+    } else if (virtcca_cvm_ram_size >= VIRTCCA_SHARED_HUGEPAGE_ADDR_LIMIT - DEFAULT_VM_GPA_START) {
+        size = VIRTCCA_SHARED_HUGEPAGE_ADDR_LIMIT - DEFAULT_VM_GPA_START;
     }
 
     virtcca_shared_hugepage = g_new(MemoryRegion, 1);
@@ -172,7 +181,9 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
                                      fb->mem_path, fb->offset, errp);
     g_free(name);
 
-    if (virtcca_cvm_enabled() && backend->share && !virtcca_shared_hugepage_mapped) {
+    if (virtcca_cvm_enabled() && backend->share &&
+        (strcmp(fb->mem_path, "/dev/shm") != 0) &&
+        !virtcca_shared_hugepage_mapped) {
         virtcca_shared_backend_memory_alloc(fb->mem_path, ram_flags, errp);
     }
 #endif
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 6c5611826c..3c31d3667e 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2063,6 +2063,7 @@ static void virt_set_memmap(VirtMachineState *vms, int pa_bits)
             if (tmi_version < MIN_TMI_VERSION_FOR_UEFI_BOOTED_CVM) {
                 vms->memmap[VIRT_MEM].base = 3 * GiB;
             }
+            virtcca_cvm_gpa_start = vms->memmap[VIRT_MEM].base;
             vms->memmap[VIRT_MEM].size = ms->ram_size;
             info_report("[qemu] fix VIRT_MEM range 0x%llx - 0x%llx\n", (unsigned long long)(vms->memmap[VIRT_MEM].base),
                  (unsigned long long)(vms->memmap[VIRT_MEM].base + ms->ram_size));
diff --git a/hw/core/numa.c b/hw/core/numa.c
index c691578ef5..98d896e687 100644
--- a/hw/core/numa.c
+++ b/hw/core/numa.c
@@ -655,7 +655,7 @@ static void virtcca_shared_memory_configuration(MachineState *ms)
     memory_region_init_alias(alias_mr, NULL, "alias-mr", virtcca_shared_hugepage,
                              0, int128_get64(virtcca_shared_hugepage->size));
     memory_region_add_subregion(address_space_virtcca_shared_memory.root,
-                                VIRTCCA_GPA_START, alias_mr);
+                                virtcca_cvm_gpa_start, alias_mr);
 }
 
 void numa_complete_configuration(MachineState *ms)
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 33778f5c64..c14dc69d27 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -243,14 +243,17 @@ typedef struct IOMMUTLBEvent {
 /* RAM FD is opened read-only */
 #define RAM_READONLY_FD (1 << 11)
 
-/* The GPA range of the VirtCCA bounce buffer is from 1GB to 4GB. */
-#define VIRTCCA_SHARED_HUGEPAGE_MAX_SIZE 0xc0000000ULL
+/* The address limit of the VirtCCA bounce buffer is 4GB. */
+#define VIRTCCA_SHARED_HUGEPAGE_ADDR_LIMIT 0x100000000ULL
 
 /* The VirtCCA shared hugepage memory granularity is 1GB */
 #define VIRTCCA_SHARED_HUGEPAGE_ALIGN 0x40000000ULL
 
-/* The GPA starting address of the VirtCCA CVM is 1GB */
-#define VIRTCCA_GPA_START 0x40000000ULL
+/* The default GPA starting address of VM is 1GB */
+#define DEFAULT_VM_GPA_START 0x40000000ULL
+
+/* The GPA starting address of the VirtCCA CVM is 1GB or 3GB */
+extern uint64_t virtcca_cvm_gpa_start;
 
 extern uint64_t virtcca_cvm_ram_size;
 
-- 
2.41.0.windows.1