Hi Yury, On Sat, Nov 25, 2017 at 10:52:21AM +0300, Yury Norov wrote: > > On Thu, Oct 12, 2017 at 12:41:12PM +0200, Christoffer Dall wrote: > > Avoid saving the guest VFP registers and restoring the host VFP > > registers on every exit from the VM. Only when we're about to run > > userspace or other threads in the kernel do we really have to switch the > > state back to the host state. > > > > We still initially configure the VFP registers to trap when entering the > > VM, but the difference is that we now leave the guest state in the > > hardware registers while running the VM. > > > > Signed-off-by: Christoffer Dall <christoffer.d...@linaro.org> > > --- > > arch/arm64/include/asm/kvm_emulate.h | 5 ++++ > > arch/arm64/include/asm/kvm_host.h | 3 +++ > > arch/arm64/kernel/asm-offsets.c | 1 + > > arch/arm64/kvm/hyp/entry.S | 3 +++ > > arch/arm64/kvm/hyp/switch.c | 47 > > +++++++++++------------------------- > > arch/arm64/kvm/hyp/sysreg-sr.c | 21 +++++++++++++--- > > 6 files changed, 44 insertions(+), 36 deletions(-) > > > > diff --git a/arch/arm64/include/asm/kvm_emulate.h > > b/arch/arm64/include/asm/kvm_emulate.h > > index 1fbfe96..630dd60 100644 > > --- a/arch/arm64/include/asm/kvm_emulate.h > > +++ b/arch/arm64/include/asm/kvm_emulate.h > > @@ -56,6 +56,11 @@ static inline unsigned long *vcpu_hcr(struct kvm_vcpu > > *vcpu) > > return (unsigned long *)&vcpu->arch.hcr_el2; > > } > > > > +static inline bool vcpu_el1_is_32bit(struct kvm_vcpu *vcpu) > > +{ > > + return (!(vcpu->arch.hcr_el2 & HCR_RW)); > > +} > > + > > static inline unsigned long *vcpu_pc(const struct kvm_vcpu *vcpu) > > { > > return (unsigned long *)&vcpu_gp_regs(vcpu)->regs.pc; > > diff --git a/arch/arm64/include/asm/kvm_host.h > > b/arch/arm64/include/asm/kvm_host.h > > index 7d3bfa7..5e09eb9 100644 > > --- a/arch/arm64/include/asm/kvm_host.h > > +++ b/arch/arm64/include/asm/kvm_host.h > > @@ -210,6 +210,9 @@ struct kvm_vcpu_arch { > > /* Guest debug state */ > > u64 debug_flags; > > > > + /* 1 if the guest VFP state is loaded into the hardware */ > > + u64 guest_vfp_loaded; > > May it be just u8/bool? > This particular field is accessed from assembly code, and I'm not sure what guarantees the compiler makes in terms of how a u8/bool is allocated with respect to padding and alignment, and I think that's why we've been using u64 fields in the past.
I don't actually remember the details, but I'd rather err on the side of caution than trying to save a few bytes. However, if someone can convince me there's a completely safe way to do this, then I'm happy to change it. Thanks, -Christoffer _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm