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authorDavid Gibson <david@gibson.dropbear.id.au>2021-01-12 11:58:04 +1100
committerDavid Gibson <david@gibson.dropbear.id.au>2021-02-08 16:57:38 +1100
commitaacdb8441376de05d9e21e93799d5a37b81f0f38 (patch)
tree54a4ee4f459f74e19f139211a430b8fdfbb04eb8 /target/i386/sev.c
parentf91f9f254ba10e94468663b23d0b780c240df268 (diff)
sev: Remove false abstraction of flash encryption
When AMD's SEV memory encryption is in use, flash memory banks (which are initialed by pc_system_flash_map()) need to be encrypted with the guest's key, so that the guest can read them. That's abstracted via the kvm_memcrypt_encrypt_data() callback in the KVM state.. except, that it doesn't really abstract much at all. For starters, the only call site is in code specific to the 'pc' family of machine types, so it's obviously specific to those and to x86 to begin with. But it makes a bunch of further assumptions that need not be true about an arbitrary confidential guest system based on memory encryption, let alone one based on other mechanisms: * it assumes that the flash memory is defined to be encrypted with the guest key, rather than being shared with hypervisor * it assumes that that hypervisor has some mechanism to encrypt data into the guest, even though it can't decrypt it out, since that's the whole point * the interface assumes that this encrypt can be done in place, which implies that the hypervisor can write into a confidential guests's memory, even if what it writes isn't meaningful So really, this "abstraction" is actually pretty specific to the way SEV works. So, this patch removes it and instead has the PC flash initialization code call into a SEV specific callback. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Diffstat (limited to 'target/i386/sev.c')
-rw-r--r--target/i386/sev.c24
1 files changed, 14 insertions, 10 deletions
diff --git a/target/i386/sev.c b/target/i386/sev.c
index b738dc45b6..8d4e1ea262 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -682,7 +682,7 @@ sev_vm_state_change(void *opaque, int running, RunState state)
}
}
-void *
+int
sev_guest_init(const char *id)
{
SevGuestState *sev;
@@ -695,7 +695,7 @@ sev_guest_init(const char *id)
ret = ram_block_discard_disable(true);
if (ret) {
error_report("%s: cannot disable RAM discard", __func__);
- return NULL;
+ return -1;
}
sev = lookup_sev_guest_info(id);
@@ -766,23 +766,27 @@ sev_guest_init(const char *id)
qemu_add_machine_init_done_notifier(&sev_machine_done_notify);
qemu_add_vm_change_state_handler(sev_vm_state_change, sev);
- return sev;
+ return 0;
err:
sev_guest = NULL;
ram_block_discard_disable(false);
- return NULL;
+ return -1;
}
int
-sev_encrypt_data(void *handle, uint8_t *ptr, uint64_t len)
+sev_encrypt_flash(uint8_t *ptr, uint64_t len, Error **errp)
{
- SevGuestState *sev = handle;
-
- assert(sev);
+ if (!sev_guest) {
+ return 0;
+ }
/* if SEV is in update state then encrypt the data else do nothing */
- if (sev_check_state(sev, SEV_STATE_LAUNCH_UPDATE)) {
- return sev_launch_update_data(sev, ptr, len);
+ if (sev_check_state(sev_guest, SEV_STATE_LAUNCH_UPDATE)) {
+ int ret = sev_launch_update_data(sev_guest, ptr, len);
+ if (ret < 0) {
+ error_setg(errp, "failed to encrypt pflash rom");
+ return ret;
+ }
}
return 0;