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

Ashish Kalra
2020-11-16T18:52:29Z

From: Brijesh Singh <brijesh.singh@amd.com>

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@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
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