Re: [PATCH] KVM: arm64: Report Protected KVM cap only if KVM is enabled

[Marc Zyngier]

On 2022-09-09 13:44, Catalin Marinas wrote:
> On Thu, Sep 01, 2022 at 09:01:22PM -0700, Elliot Berman wrote:
> > If "kvm-arm.mode=protected" is present on kernel command line, but the
> > kernel doesn't actually support KVM because it booted from EL1, the
> > ARM64_KVM_PROTECTED_MODE capability is misleadingly reported as 
> > present.
> > Fix this by adding a check whether we booted from EL2.
> >
> > Cc: Will Deacon <will@xxxxxxxxxx>
> > Cc: David Brazdil <dbrazdil@xxxxxxxxxx>
> > Cc: Marc Zyngier <maz@xxxxxxxxxx>
> > Signed-off-by: Elliot Berman <quic_eberman@xxxxxxxxxxx>
> > ---
> >  arch/arm64/kernel/cpufeature.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/arm64/kernel/cpufeature.c 
> > b/arch/arm64/kernel/cpufeature.c
> > index 8d88433de81d..866667be0651 100644
> > --- a/arch/arm64/kernel/cpufeature.c
> > +++ b/arch/arm64/kernel/cpufeature.c
> > @@ -1974,7 +1974,7 @@ static void cpu_enable_mte(struct 
> > arm64_cpu_capabilities const *cap)
> >  #ifdef CONFIG_KVM
> >  static bool is_kvm_protected_mode(const struct arm64_cpu_capabilities 
> > *entry, int __unused)
> >  {
> > -	return kvm_get_mode() == KVM_MODE_PROTECTED;
> > +	return is_hyp_mode_available() && kvm_get_mode() == 
> > KVM_MODE_PROTECTED;
> >  }
> >  #endif /* CONFIG_KVM */
>
> Could we not fix this in early_kvm_mode_cfg()?

That's be indeed preferable.

Thanks,

        M.
--
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