Re: [PATCH v1 6/9] KVM: x86: Add Heki hypervisor support

From: Mickaël Salaün
Date: Fri May 26 2023 - 12:49:29 EST

On 08/05/2023 23:18, Wei Liu wrote:
On Fri, May 05, 2023 at 05:20:43PM +0200, Mickaël Salaün wrote:
From: Madhavan T. Venkataraman <madvenka@xxxxxxxxxxxxxxxxxxx>

Each supported hypervisor in x86 implements a struct x86_hyper_init to
define the init functions for the hypervisor. Define a new init_heki()
entry point in struct x86_hyper_init. Hypervisors that support Heki
must define this init_heki() function. Call init_heki() of the chosen
hypervisor in init_hypervisor_platform().

Create a heki_hypervisor structure that each hypervisor can fill
with its data and functions. This will allow the Heki feature to work
in a hypervisor agnostic way.

Declare and initialize a "heki_hypervisor" structure for KVM so KVM can
support Heki. Define the init_heki() function for KVM. In init_heki(),
set the hypervisor field in the generic "heki" structure to the KVM
"heki_hypervisor". After this point, generic Heki code can access the
KVM Heki data and functions.

+static void kvm_init_heki(void)
+ long err;
+ if (!kvm_para_available())
+ /* Cannot make KVM hypercalls. */
+ return;
+ err = kvm_hypercall3(KVM_HC_LOCK_MEM_PAGE_RANGES, -1, -1, -1);

Why not do a proper version check or capability check here? If the ABI
or supported features ever change then we have something to rely on?

The attributes will indeed get extended, but I wanted to have a simple proposal for now.

Do you mean to get the version of this hypercall e.g., with a dedicated flag, like with the landlock_create_ruleset/LANDLOCK_CREATE_RULESET_VERSION syscall?