[PATCH v12 21/28] sev/i386: add debug encrypt and decrypt commands

[Brijesh Singh <brijesh.singh@xxxxxxx>]

KVM_SEV_DBG_DECRYPT and KVM_SEV_DBG_ENCRYPT commands are used for
decrypting and encrypting guest memory region. The command works only if
the guest policy allows the debugging.

Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Richard Henderson <rth@xxxxxxxxxxx>
Cc: Eduardo Habkost <ehabkost@xxxxxxxxxx>
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
---
 accel/kvm/kvm-all.c      |  1 +
 stubs/sev.c              |  4 ++++
 target/i386/sev.c        | 57 ++++++++++++++++++++++++++++++++++++++++++++++++
 target/i386/trace-events |  1 +
 4 files changed, 63 insertions(+)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 411aa87719e6..8089173491dd 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -1682,6 +1682,7 @@ static int kvm_init(MachineState *ms)
         }
 
         kvm_state->memcrypt_encrypt_data = sev_encrypt_data;
+        kvm_state->memcrypt_debug_ops = sev_set_debug_ops;
     }
 
     ret = kvm_arch_init(ms, s);
diff --git a/stubs/sev.c b/stubs/sev.c
index 2e20f3b73a5b..73f5c7f93a67 100644
--- a/stubs/sev.c
+++ b/stubs/sev.c
@@ -15,6 +15,10 @@
 #include "qemu-common.h"
 #include "sysemu/sev.h"
 
+void sev_set_debug_ops(void *handle, MemoryRegion *mr)
+{
+}
+
 int sev_encrypt_data(void *handle, uint8_t *ptr, uint64_t len)
 {
     return 1;
diff --git a/target/i386/sev.c b/target/i386/sev.c
index ce199d259f7a..f687e9e40e32 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -29,6 +29,7 @@
 #define DEFAULT_SEV_DEVICE      "/dev/sev"
 
 static SEVState *sev_state;
+static MemoryRegionRAMReadWriteOps  sev_ops;
 
 static const char *const sev_fw_errlist[] = {
     "",
@@ -606,6 +607,46 @@ sev_vm_state_change(void *opaque, int running, RunState state)
     }
 }
 
+static int
+sev_dbg_enc_dec(uint8_t *dst, const uint8_t *src, uint32_t len, bool write)
+{
+    int ret, error;
+    struct kvm_sev_dbg dbg;
+
+    dbg.src_uaddr = (unsigned long)src;
+    dbg.dst_uaddr = (unsigned long)dst;
+    dbg.len = len;
+
+    trace_kvm_sev_debug(write ? "encrypt" : "decrypt", src, dst, len);
+    ret = sev_ioctl(sev_state->sev_fd,
+                    write ? KVM_SEV_DBG_ENCRYPT : KVM_SEV_DBG_DECRYPT,
+                    &dbg, &error);
+    if (ret) {
+        error_report("%s (%s) %#llx->%#llx+%#x ret=%d fw_error=%d '%s'",
+                     __func__, write ? "write" : "read", dbg.src_uaddr,
+                     dbg.dst_uaddr, dbg.len, ret, error,
+                     fw_error_to_str(error));
+    }
+
+    return ret;
+}
+
+static int
+sev_mem_read(uint8_t *dst, const uint8_t *src, uint32_t len, MemTxAttrs attrs)
+{
+    assert(attrs.debug);
+
+    return sev_dbg_enc_dec(dst, src, len, false);
+}
+
+static int
+sev_mem_write(uint8_t *dst, const uint8_t *src, uint32_t len, MemTxAttrs attrs)
+{
+    assert(attrs.debug);
+
+    return sev_dbg_enc_dec(dst, src, len, true);
+}
+
 void *
 sev_guest_init(const char *id)
 {
@@ -706,6 +747,22 @@ sev_encrypt_data(void *handle, uint8_t *ptr, uint64_t len)
     return 0;
 }
 
+void
+sev_set_debug_ops(void *handle, MemoryRegion *mr)
+{
+    SEVState *s = (SEVState *)handle;
+
+    /* If policy does not allow debug then no need to register ops */
+    if (s->policy & SEV_POLICY_NODBG) {
+        return;
+    }
+
+    sev_ops.read = sev_mem_read;
+    sev_ops.write = sev_mem_write;
+
+    memory_region_set_ram_debug_ops(mr, &sev_ops);
+}
+
 static void
 sev_register_types(void)
 {
diff --git a/target/i386/trace-events b/target/i386/trace-events
index b1fbde6e40fe..00aa6e98d810 100644
--- a/target/i386/trace-events
+++ b/target/i386/trace-events
@@ -15,3 +15,4 @@ kvm_sev_launch_start(int policy, void *session, void *pdh) "policy 0x%x session
 kvm_sev_launch_update_data(void *addr, uint64_t len) "addr %p len 0x%" PRIu64
 kvm_sev_launch_measurement(const char *value) "data %s"
 kvm_sev_launch_finish(void) ""
+kvm_sev_debug(const char *op, const uint8_t *src, uint8_t *dst, int len) "(%s) src %p dst %p len %d"
-- 
2.14.3