On Thu, 2018-07-05 at 14:51 +0100, Mark Rutland wrote:
> On Sun, Apr 15, 2018 at 12:26:44AM +0200, KarimAllah Ahmed wrote:
> >
> > Switch 'requests' to be explicitly 64-bit and update BUILD_BUG_ON check to
> > use the size of "requests" instead of the hard-coded '32'.
> >
> > That gives us a bit more room again for arch-specific requests as we
> > already ran out of space for x86 due to the hard-coded check.
> >
> > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> > Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
> > Cc: kvm@xxxxxxxxxxxxxxx
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > Signed-off-by: KarimAllah Ahmed <karahmed@xxxxxxxxx>
> > ---
> > include/linux/kvm_host.h | 10 +++++-----
> > 1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > index 6930c63..fe4f46b 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -129,7 +129,7 @@ static inline bool is_error_page(struct page *page)
> > #define KVM_REQUEST_ARCH_BASE 8
> >
> > #define KVM_ARCH_REQ_FLAGS(nr, flags) ({ \
> > - BUILD_BUG_ON((unsigned)(nr) >= 32 - KVM_REQUEST_ARCH_BASE); \
> > + BUILD_BUG_ON((unsigned)(nr) >= (sizeof(((struct kvm_vcpu *)0)->requests) * 8) - KVM_REQUEST_ARCH_BASE); \
> > (unsigned)(((nr) + KVM_REQUEST_ARCH_BASE) | (flags)); \
> > })
> > #define KVM_ARCH_REQ(nr) KVM_ARCH_REQ_FLAGS(nr, 0)
> > @@ -223,7 +223,7 @@ struct kvm_vcpu {
> > int vcpu_id;
> > int srcu_idx;
> > int mode;
> > - unsigned long requests;
> > + u64 requests;
>
> The usual thing to do for bitmaps is something like:
>
> #define KVM_REQUEST_NR (KVM_REQUEST_ARCH_BASE + KVM_REQUEST_ARCH_NR)
>
> unsigned long requests[BITS_TO_LONGS(NR_KVM_REQUESTS)];
>
> >
> > unsigned long guest_debug;
> >
> > int pre_pcpu;
> > @@ -1122,7 +1122,7 @@ static inline void kvm_make_request(int req, struct kvm_vcpu *vcpu)
> > * caller. Paired with the smp_mb__after_atomic in kvm_check_request.
> > */
> > smp_wmb();
> > - set_bit(req & KVM_REQUEST_MASK, &vcpu->requests);
> > + set_bit(req & KVM_REQUEST_MASK, (void *)&vcpu->requests);
>
> ... which wouldn't require a void cast to make the bit API functions
> happy (as these expect a pointer to the first unsigned long in the
> bitmap).
Ah, right! Good point.
Paolo,
Would you prefer to switch "requests" to a bitmap and
update kvm_request_pending to handle this?
>
> Thanks,
> Mark.
>
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