[PATCH 08/11] sev/i386: add debug encrypt and decrypt commands

[Ashish Kalra <Ashish.Kalra@xxxxxxx>]

From: Brijesh Singh <brijesh.singh@xxxxxxx>

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

Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
---
 accel/kvm/kvm-all.c      |  2 ++
 accel/kvm/sev-stub.c     |  4 +++
 include/sysemu/sev.h     |  1 +
 target/i386/sev.c        | 58 ++++++++++++++++++++++++++++++++++++++++
 target/i386/trace-events |  1 +
 5 files changed, 66 insertions(+)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index ae85f53e7d..042205e3e1 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -2232,6 +2232,8 @@ static int kvm_init(MachineState *ms)
         }
 
         kvm_state->memcrypt_encrypt_data = sev_encrypt_data;
+        kvm_state->memcrypt_debug_ops_memory_region =
+            sev_set_debug_ops_memory_region;
     }
 
     ret = kvm_arch_init(ms, s);
diff --git a/accel/kvm/sev-stub.c b/accel/kvm/sev-stub.c
index 4f97452585..3f1f0ef217 100644
--- a/accel/kvm/sev-stub.c
+++ b/accel/kvm/sev-stub.c
@@ -15,6 +15,10 @@
 #include "qemu-common.h"
 #include "sysemu/sev.h"
 
+void sev_set_debug_ops_memory_region(void *handle, MemoryRegion *mr)
+{
+}
+
 int sev_encrypt_data(void *handle, uint8_t *ptr, uint64_t len)
 {
     abort();
diff --git a/include/sysemu/sev.h b/include/sysemu/sev.h
index 98c1ec8d38..6c37247915 100644
--- a/include/sysemu/sev.h
+++ b/include/sysemu/sev.h
@@ -18,4 +18,5 @@
 
 void *sev_guest_init(const char *id);
 int sev_encrypt_data(void *handle, uint8_t *ptr, uint64_t len);
+void sev_set_debug_ops_memory_region(void *handle, MemoryRegion *mr);
 #endif
diff --git a/target/i386/sev.c b/target/i386/sev.c
index 93c4d60b82..3036fb3e43 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -72,6 +72,8 @@ struct SevGuestState {
 static SevGuestState *sev_guest;
 static Error *sev_mig_blocker;
 
+static MemoryRegionRAMReadWriteOps sev_ops;
+
 static const char *const sev_fw_errlist[] = {
     "",
     "Platform state is invalid",
@@ -679,6 +681,46 @@ 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_guest->sev_fd,
+                    write ? KVM_SEV_DBG_ENCRYPT : KVM_SEV_DBG_DECRYPT,
+                    &dbg, &error);
+    if (ret) {
+        error_report("%s (%s) 0x%llx->0x%llx+0x%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)
 {
@@ -785,6 +827,22 @@ sev_encrypt_data(void *handle, uint8_t *ptr, uint64_t len)
     return 0;
 }
 
+void
+sev_set_debug_ops_memory_region(void *handle, MemoryRegion *mr)
+{
+    SevGuestState *s = 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 789c700d4a..f91213c5e9 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"
-- 
2.17.1