[PATCH 02/11] exec: Add new MemoryDebugOps.

Ashish Kalra
2020-11-16T18:49:37Z

From: Ashish Kalra <ashish.kalra@amd.com>

Introduce new MemoryDebugOps which hook into guest virtual and physical
memory debug interfaces such as cpu_memory_rw_debug, to allow vendor specific
assist/hooks for debugging and delegating accessing the guest memory.
This is required for example in case of AMD SEV platform where the guest
memory is encrypted and a SEV specific debug assist/hook will be required
to access the guest memory.

The MemoryDebugOps are used by cpu_memory_rw_debug() and default to
address_space_read and address_space_write_rom.

Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
include/exec/memory.h | 11 +++++++++++
softmmu/physmem.c | 24 ++++++++++++++++++++----
2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/include/exec/memory.h b/include/exec/memory.h
index aff6ef7605..73deb4b456 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -2394,6 +2394,17 @@ MemTxResult address_space_write_cached_slow(MemoryRegionCache *cache,
hwaddr addr, const void *buf,
hwaddr len);

+typedef struct MemoryDebugOps {
+ MemTxResult (*read)(AddressSpace *as, hwaddr phys_addr,
+ MemTxAttrs attrs, void *buf,
+ hwaddr len);
+ MemTxResult (*write)(AddressSpace *as, hwaddr phys_addr,
+ MemTxAttrs attrs, const void *buf,
+ hwaddr len);
+} MemoryDebugOps;
+
+void address_space_set_debug_ops(const MemoryDebugOps *ops);
+
static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write)
{
if (is_write) {
diff --git a/softmmu/physmem.c b/softmmu/physmem.c
index a9adedb9f8..057d6d4ce1 100644
--- a/softmmu/physmem.c
+++ b/softmmu/physmem.c
@@ -166,6 +166,18 @@ struct DirtyBitmapSnapshot {
unsigned long dirty[];
};

+static const MemoryDebugOps default_debug_ops = {
+ .read = address_space_read,
+ .write = address_space_write_rom
+};
+
+static const MemoryDebugOps *debug_ops = &default_debug_ops;
+
+void address_space_set_debug_ops(const MemoryDebugOps *ops)
+{
+ debug_ops = ops;
+}
+
static void phys_map_node_reserve(PhysPageMap *map, unsigned nodes)
{
static unsigned alloc_hint = 16;
@@ -3407,6 +3419,10 @@ int cpu_memory_rw_debug(CPUState *cpu, target_ulong addr,
page = addr & TARGET_PAGE_MASK;
phys_addr = cpu_get_phys_page_attrs_debug(cpu, page, &attrs);
asidx = cpu_asidx_from_attrs(cpu, attrs);
+
+ /* set debug attrs to indicate memory access is from the debugger */
+ attrs.debug = 1;
+
/* if no physical page mapped, return an error */
if (phys_addr == -1)
return -1;
@@ -3415,11 +3431,11 @@ int cpu_memory_rw_debug(CPUState *cpu, target_ulong addr,
l = len;
phys_addr += (addr & ~TARGET_PAGE_MASK);
if (is_write) {
- res = address_space_write_rom(cpu->cpu_ases[asidx].as, phys_addr,
- attrs, buf, l);
+ res = debug_ops->write(cpu->cpu_ases[asidx].as, phys_addr,
+ attrs, buf, l);
} else {
- res = address_space_read(cpu->cpu_ases[asidx].as, phys_addr,
- attrs, buf, l);
+ res = debug_ops->read(cpu->cpu_ases[asidx].as, phys_addr,
+ attrs, buf, l);
}
if (res != MEMTX_OK) {
return -1;
--
2.17.1