On Fri, Oct 30, 2026, Gautam Menghani wrote: > On Wed, Oct 28, 2026 at 12:02:55PM -0700, Sean Christopherson wrote: > > Explicitly force an IPI when invoking kvm_vcpu_kick() directly instead of > > relying on kvm_arch_vcpu_should_kick() to unconditionally return 1/true. > > This will allow dropping kvm_arch_vcpu_should_kick() in favor of > > kvm_request_needs_ipi(). > > > > No functional change intended (1 || 1 == true). > > > > Signed-off-by: Sean Christopherson <[email protected]> > > --- > > arch/powerpc/include/asm/kvm_ppc.h | 13 ++++++++++++- > > arch/powerpc/kvm/book3s.c | 4 ++-- > > arch/powerpc/kvm/book3s_pr.c | 2 +- > > arch/powerpc/kvm/booke.c | 6 +++--- > > arch/powerpc/kvm/e500_emulate.c | 2 +- > > arch/powerpc/kvm/powerpc.c | 2 +- > > 6 files changed, 20 insertions(+), 9 deletions(-) > > > > diff --git a/arch/powerpc/include/asm/kvm_ppc.h > > b/arch/powerpc/include/asm/kvm_ppc.h > > index 169ea6a7fbad..bbe7378ad0ef 100644 > > --- a/arch/powerpc/include/asm/kvm_ppc.h > > +++ b/arch/powerpc/include/asm/kvm_ppc.h > > @@ -30,6 +30,17 @@ > > #endif > > #include <asm/inst.h> > > > > +/* > > + * TODO: For unknown reasons, KVM PPC has historically ignored vcpu->mode > > when > > + * determining if kicking a vCPU needs an IPI. Either document why > > that > > + * behavior is necessary, or drop this helper and the @force param > > from > > + * __kvm_vcpu_kick(). > > + */ > > +static inline void kvmppc_vcpu_kick(struct kvm_vcpu *vcpu) > > +{ > > + __kvm_vcpu_kick(vcpu, false, true); > > +} > > + > > AFAICS, there is no reason for PPC to always return 1. I was looking at > the old patches on mailing list and found this - > https://lore.kernel.org/kvm/[email protected] > > ``` > How about we return 1 for kvm_arch_vcpu_in_guest_mode() on !x86 always, just > like it's done today basically? Then we can worry about needless IPIs later > and don't regress from the respective current kick implementations. > ```
FWIW, I found that as well, but there are a metric ton of kvm_vcpu_kick() calls that have been added since then, and they scared me. > However, I'll do some testing and get back by mid next week to make sure > there are no suprises. Thanks! If we can drop the PPC behavior, that would be wonderful! Though if we do that, it should be for 7.5 in a follow-up (this series really should go into 7.4 due to the SNP issue).
