On Thu, Jul 15, 2021 at 05:31:50PM +0100, Marc Zyngier wrote: > Plumb in the hypercall interface to allow a guest to discover, > enroll, map and unmap MMIO regions. > > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> > --- > arch/arm64/kvm/hypercalls.c | 20 ++++++++++++++++++++ > include/linux/arm-smccc.h | 28 ++++++++++++++++++++++++++++ > 2 files changed, 48 insertions(+) > > diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c > index 30da78f72b3b..a3deeb907fdd 100644 > --- a/arch/arm64/kvm/hypercalls.c > +++ b/arch/arm64/kvm/hypercalls.c > @@ -5,6 +5,7 @@ > #include <linux/kvm_host.h> > > #include <asm/kvm_emulate.h> > +#include <asm/kvm_mmu.h> > > #include <kvm/arm_hypercalls.h> > #include <kvm/arm_psci.h> > @@ -129,10 +130,29 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu) > case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID: > val[0] = BIT(ARM_SMCCC_KVM_FUNC_FEATURES); > val[0] |= BIT(ARM_SMCCC_KVM_FUNC_PTP); > + val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MMIO_GUARD_INFO); > + val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MMIO_GUARD_ENROLL); > + val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MMIO_GUARD_MAP); > + val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MMIO_GUARD_UNMAP); > break; > case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID: > kvm_ptp_get_time(vcpu, val); > break; > + case ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_INFO_FUNC_ID: > + val[0] = PAGE_SIZE; > + break; I get the nagging feeling that querying the stage-2 page-size outside of MMIO guard is going to be useful once we start looking at memory sharing, so perhaps rename this to something more generic? > + case ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_ENROLL_FUNC_ID: > + set_bit(KVM_ARCH_FLAG_MMIO_GUARD, &vcpu->kvm->arch.flags); > + val[0] = SMCCC_RET_SUCCESS; > + break; > + case ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_MAP_FUNC_ID: > + if (kvm_install_ioguard_page(vcpu, vcpu_get_reg(vcpu, 1))) > + val[0] = SMCCC_RET_SUCCESS; > + break; > + case ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_UNMAP_FUNC_ID: > + if (kvm_remove_ioguard_page(vcpu, vcpu_get_reg(vcpu, 1))) > + val[0] = SMCCC_RET_SUCCESS; > + break; I think there's a slight discrepancy between MAP and UNMAP here in that calling UNMAP on something that hasn't been mapped will fail, whereas calling MAP on something that's already been mapped will succeed. I think that might mean you can't reason about the final state of the page if two vCPUs race to call these functions in some cases (and both succeed). Will
