On Mon, 17 Jan 2022 17:06:10 +0000,
"Russell King (Oracle)" <linux@xxxxxxxxxxxxxxx> wrote:
>
> On Mon, Nov 29, 2021 at 08:00:49PM +0000, Marc Zyngier wrote:
> > From: Christoffer Dall <christoffer.dall@xxxxxxx>
> >
> > Reset the VCPU with PSTATE.M = EL2h when the nested virtualization
> > feature is enabled on the VCPU.
> >
> > Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxx>
> > [maz: rework register reset not to use empty data structures]
> > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
>
> Reviewed-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx>
>
> However, a couple of comments below.
>
> > ---
> > arch/arm64/kvm/reset.c | 10 ++++++++--
> > 1 file changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
> > index 426bd7fbc3fd..38a7182819fb 100644
> > --- a/arch/arm64/kvm/reset.c
> > +++ b/arch/arm64/kvm/reset.c
> > @@ -27,6 +27,7 @@
> > #include <asm/kvm_asm.h>
> > #include <asm/kvm_emulate.h>
> > #include <asm/kvm_mmu.h>
> > +#include <asm/kvm_nested.h>
> > #include <asm/virt.h>
> >
> > /* Maximum phys_shift supported for any VM on this host */
> > @@ -38,6 +39,9 @@ static u32 kvm_ipa_limit;
> > #define VCPU_RESET_PSTATE_EL1 (PSR_MODE_EL1h | PSR_A_BIT | PSR_I_BIT | \
> > PSR_F_BIT | PSR_D_BIT)
> >
> > +#define VCPU_RESET_PSTATE_EL2 (PSR_MODE_EL2h | PSR_A_BIT | PSR_I_BIT | \
> > + PSR_F_BIT | PSR_D_BIT)
> > +
> > #define VCPU_RESET_PSTATE_SVC (PSR_AA32_MODE_SVC | PSR_AA32_A_BIT | \
> > PSR_AA32_I_BIT | PSR_AA32_F_BIT)
> >
> > @@ -176,8 +180,8 @@ static bool vcpu_allowed_register_width(struct kvm_vcpu *vcpu)
> > if (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1) && is32bit)
> > return false;
> >
> > - /* MTE is incompatible with AArch32 */
> > - if (kvm_has_mte(vcpu->kvm) && is32bit)
> > + /* MTE and NV are incompatible with AArch32 */
> > + if ((kvm_has_mte(vcpu->kvm) || nested_virt_in_use(vcpu)) && is32bit)
> > return false;
>
> It seems we have a bunch of:
>
> if (something && is32bit)
> return false;
>
> tests here - would it make sense to do:
>
> if (is32bit) {
> if (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1))
> return false;
>
> /* MTE is incompatible with AArch32 */
> if (kvm_has_mte(vcpu->kvm))
> return false;
>
> /* NV is incompatible with AArch32 */
> if (nested_virt_in_use(vcpu))
> return false;
> }
>
> in terms of improved readability?
Agreed. I've now reworked to follow this pattern.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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