Re: [kvm-unit-tests PATCH v2 0/9] arm64: support EL2

[Alexandru Elisei <alexandru.elisei@arm.com>]

Hi Joey,

On Thu, May 29, 2025 at 02:55:48PM +0100, Joey Gouly wrote:
> Hi all,
> 
> This series is for adding support to running the kvm-unit-tests at EL2. These
> have been tested with Marc Zyngier's Linux kvm-arm64/nv-next branch [1] and
> kvmtool branch arm64/nv-6.13 [2]
> 
> The goal is to later extend and add new tests for Nested Virtualisation,
> however they should also work with bare metal as well.
> 
> Changes since v1[3]:
> 	- Authorship fixed on 2 patches
> 	- Tested and fixed EFI support
> 	- Recactored assembly and added init_el macro
> 	- Clear trap registers, trying to avoid relying on default register
> 	  state
> 	- Cleaned up PMU changes
> 
> The debug tests fail with --nested, but pass with --nested --e2h0, I
> need to investigate this.

That's because the code does not check for the absence of FEAT_E2H0, and it sets
HCR_EL2.E2H to 0 when writing INIT_HCR_EL2_EL1_ONLY even if KVM doesn't support
that.

Have you considered using parts of el2_setup.h as-is instead of rolling out your
own EL2 init code? When I was looking at the init_el macro I was comparing it
with el2_setup.h, and having some of the code shared would make things easier
with updates and fixes too.

Either way, not a deal breaker if you want to write your own init code.

Thanks,
Alex

> 
> Thanks,
> Joey
> 
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git kvm-arm64/nv-next (commit a35d752b17f4)
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/maz/kvmtool.git arm64/nv-6.13 (commit 5b6fe295ea7)
> [3] https://lore.kernel.org/kvmarm/20250220141354.2565567-1-joey.gouly@arm.com/
> 
> Alexandru Elisei (2):
>   arm64: micro-bench: use smc when at EL2
>   arm64: selftest: update test for running at EL2
> 
> Joey Gouly (7):
>   arm64: drop to EL1 if booted at EL2
>   arm64: efi: initialise SCTLR_ELx fully
>   arm64: efi: initialise the EL
>   arm64: timer: use hypervisor timers when at EL2
>   arm64: micro-bench: fix timer IRQ
>   arm64: pmu: count EL2 cycles
>   arm64: run at EL2 if supported
> 
>  arm/cstart64.S             | 56 ++++++++++++++++++++++++++++++++++++--
>  arm/efi/crt0-efi-aarch64.S |  5 ++++
>  arm/micro-bench.c          | 26 ++++++++++++++++--
>  arm/pmu.c                  | 13 ++++++---
>  arm/selftest.c             | 18 ++++++++----
>  arm/timer.c                | 10 +++++--
>  lib/acpi.h                 |  2 ++
>  lib/arm/asm/setup.h        |  1 +
>  lib/arm/asm/timer.h        | 11 ++++++++
>  lib/arm/setup.c            |  6 ++++
>  lib/arm/timer.c            | 19 +++++++++++--
>  lib/arm64/asm/sysreg.h     | 19 +++++++++++++
>  12 files changed, 167 insertions(+), 19 deletions(-)
> 
> -- 
> 2.25.1
>