On Wed, 08 Jun 2022 16:16:55 +0100,
Fuad Tabba <tabba@xxxxxxxxxx> wrote:
>
> Hi Marc,
>
> On Sat, May 28, 2022 at 12:49 PM Marc Zyngier <maz@xxxxxxxxxx> wrote:
> >
> > We really don't want PENDING_EXCEPTION and INCREMENT_PC to ever be
> > set at the same time, as they are mutually exclusive. Add checks
> > that will generate a warning should this ever happen.
> >
> > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> > ---
> > arch/arm64/include/asm/kvm_emulate.h | 1 +
> > arch/arm64/kvm/hyp/nvhe/sys_regs.c | 2 ++
> > arch/arm64/kvm/inject_fault.c | 8 ++++++++
> > 3 files changed, 11 insertions(+)
> >
> > diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
> > index 46e631cd8d9e..861fa0b24a7f 100644
> > --- a/arch/arm64/include/asm/kvm_emulate.h
> > +++ b/arch/arm64/include/asm/kvm_emulate.h
> > @@ -473,6 +473,7 @@ static inline unsigned long vcpu_data_host_to_guest(struct kvm_vcpu *vcpu,
> >
> > static __always_inline void kvm_incr_pc(struct kvm_vcpu *vcpu)
> > {
> > + WARN_ON(vcpu_get_flag(vcpu, PENDING_EXCEPTION));
> > vcpu_set_flag(vcpu, INCREMENT_PC);
> > }
> >
> > diff --git a/arch/arm64/kvm/hyp/nvhe/sys_regs.c b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
> > index 2841a2d447a1..04973984b6db 100644
> > --- a/arch/arm64/kvm/hyp/nvhe/sys_regs.c
> > +++ b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
> > @@ -38,6 +38,8 @@ static void inject_undef64(struct kvm_vcpu *vcpu)
> > *vcpu_pc(vcpu) = read_sysreg_el2(SYS_ELR);
> > *vcpu_cpsr(vcpu) = read_sysreg_el2(SYS_SPSR);
> >
> > + WARN_ON(vcpu_get_flag(vcpu, INCREMENT_PC));
> > +
> > vcpu_set_flag(vcpu, PENDING_EXCEPTION);
> > vcpu_set_flag(vcpu, EXCEPT_AA64_EL1_SYNC);
> >
> > diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c
> > index a9a7b513f3b0..2f4b9afc16ec 100644
> > --- a/arch/arm64/kvm/inject_fault.c
> > +++ b/arch/arm64/kvm/inject_fault.c
> > @@ -20,6 +20,8 @@ static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr
> > bool is_aarch32 = vcpu_mode_is_32bit(vcpu);
> > u32 esr = 0;
> >
> > + WARN_ON(vcpu_get_flag(vcpu, INCREMENT_PC));
> > +
>
> Minor nit: While we're at it, should we just create a helper for
> setting PENDING_EXCEPTION, same as we have for INCREMENT_PC? That
> might make the code clearer and save us from the hassle of having this
> WARN_ON before every instance of setting PENDING_EXCEPTION?
Good point. I ended up with this:
#define kvm_pend_exception(v, e) \
do { \
WARN_ON(vcpu_get_flag((v), INCREMENT_PC)); \
vcpu_set_flag((v), PENDING_EXCEPTION); \
vcpu_set_flag((v), e); \
} while (0)
It has to be a macro in order to deal with the flag expansion, but is
otherwise a welcome cleanup.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
