Commit Graph

6 Commits

Author SHA1 Message Date
David Gibson
ec78e2cda3 confidential guest support: Move SEV initialization into arch specific code
While we've abstracted some (potential) differences between mechanisms for
securing guest memory, the initialization is still specific to SEV.  Given
that, move it into x86's kvm_arch_init() code, rather than the generic
kvm_init() code.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
2021-02-08 16:57:38 +11:00
David Gibson
c9f5aaa6bc sev: Add Error ** to sev_kvm_init()
This allows failures to be reported richly and idiomatically.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
2021-02-08 16:57:38 +11:00
David Gibson
e0292d7c62 confidential guest support: Rework the "memory-encryption" property
Currently the "memory-encryption" property is only looked at once we
get to kvm_init().  Although protection of guest memory from the
hypervisor isn't something that could really ever work with TCG, it's
not conceptually tied to the KVM accelerator.

In addition, the way the string property is resolved to an object is
almost identical to how a QOM link property is handled.

So, create a new "confidential-guest-support" link property which sets
this QOM interface link directly in the machine.  For compatibility we
keep the "memory-encryption" property, but now implemented in terms of
the new property.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
2021-02-08 16:57:38 +11:00
David Gibson
aacdb84413 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>
2021-02-08 16:57:38 +11:00
Brijesh Singh
54e8953967 kvm: introduce memory encryption APIs
Inorder to integerate the Secure Encryption Virtualization (SEV) support
add few high-level memory encryption APIs which can be used for encrypting
the guest memory region.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-03-13 12:04:03 +01:00
Brijesh Singh
b20e37801f kvm: add memory encryption context
Split from a patch by Brijesh Singh (brijesh.singh@amd.com).

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
2018-03-13 12:04:03 +01:00