2025-04-28T17:52:25+05:30, Anup Patel <anup@xxxxxxxxxxxxxx>: > On Thu, Apr 3, 2025 at 5:02 PM Radim Krčmář <rkrcmar@xxxxxxxxxxxxxxxx> wrote: >> For a cleaner solution, we should add interfaces to perform the KVM-SBI >> reset request on userspace demand. I think it would also be much better >> if userspace was in control of the post-reset state. > > Apart from breaking KVM user-space, this patch is incorrect and > does not align with the: > 1) SBI spec > 2) OS boot protocol. > > The SBI spec only defines the entry state of certain CPU registers > (namely, PC, A0, and A1) when CPU enters S-mode: > 1) Upon SBI HSM start call from some other CPU > 2) Upon resuming from non-retentive SBI HSM suspend or > SBI system suspend > > The S-mode entry state of the boot CPU is defined by the > OS boot protocol and not by the SBI spec. Due to this, reason > KVM RISC-V expects user-space to set up the S-mode entry > state of the boot CPU upon system reset. We can handle the initial state consistency in other patches. What needs addressing is a way to trigger the KVM reset from userspace, even if only to clear the internal KVM state. I think mp_state is currently the best signalization that KVM should reset, so I added it there. What would be your preferred interface for that? Thanks.
