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sev/i386: register the guest memory range which may contain encrypted data

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When SEV is enabled, the hardware encryption engine uses a tweak such
that the two identical plaintext at different location will have a
different ciphertexts. So swapping or moving a ciphertexts of two guest
pages will not result in plaintexts being swapped. Hence relocating
a physical backing pages of the SEV guest will require some additional
steps in KVM driver. The KVM_MEMORY_ENCRYPT_{UN,}REG_REGION ioctl can be
used to register/unregister the guest memory region which may contain the
encrypted data. KVM driver will internally handle the relocating physical
backing pages of registered memory regions.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Brijesh Singh 2018-03-08 06:48:45 -06:00 committed by Paolo Bonzini
parent d8575c6c02
commit 2b308e4431
2 changed files with 44 additions and 0 deletions
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42
target/i386/sev.c
View File

@ -105,6 +105,46 @@ fw_error_to_str(int code)
return sev_fw_errlist[code];
}
static void
sev_ram_block_added(RAMBlockNotifier *n, void *host, size_t size)
{
int r;
struct kvm_enc_region range;
range.addr = (__u64)(unsigned long)host;
range.size = size;
trace_kvm_memcrypt_register_region(host, size);
r = kvm_vm_ioctl(kvm_state, KVM_MEMORY_ENCRYPT_REG_REGION, &range);
if (r) {
error_report("%s: failed to register region (%p+%#zx) error '%s'",
__func__, host, size, strerror(errno));
exit(1);
}
}
static void
sev_ram_block_removed(RAMBlockNotifier *n, void *host, size_t size)
{
int r;
struct kvm_enc_region range;
range.addr = (__u64)(unsigned long)host;
range.size = size;
trace_kvm_memcrypt_unregister_region(host, size);
r = kvm_vm_ioctl(kvm_state, KVM_MEMORY_ENCRYPT_UNREG_REGION, &range);
if (r) {
error_report("%s: failed to unregister region (%p+%#zx)",
__func__, host, size);
}
}
static struct RAMBlockNotifier sev_ram_notifier = {
.ram_block_added = sev_ram_block_added,
.ram_block_removed = sev_ram_block_removed,
};
static void
qsev_guest_finalize(Object *obj)
{
@ -436,6 +476,8 @@ sev_guest_init(const char *id)
goto err;
}
ram_block_notifier_add(&sev_ram_notifier);
return s;
err:
g_free(sev_state);

2
target/i386/trace-events
View File

@ -8,3 +8,5 @@ kvm_x86_update_msi_routes(int num) "Updated %d MSI routes"
# target/i386/sev.c
kvm_sev_init(void) ""
kvm_memcrypt_register_region(void *addr, size_t len) "addr %p len 0x%zu"
kvm_memcrypt_unregister_region(void *addr, size_t len) "addr %p len 0x%zu"