Il 03/07/2013 13:45, Cornelia Huck ha scritto: > On Wed, 03 Jul 2013 12:58:00 +0200 > Paolo Bonzini <[email protected]> wrote: > >> Il 03/07/2013 12:51, Cornelia Huck ha scritto: >>> On Wed, 03 Jul 2013 11:21:23 +0200 >>> Paolo Bonzini <[email protected]> wrote: >>> >>>> Il 03/07/2013 11:05, Paolo Bonzini ha scritto: >>>>> Nice idea, though I don't really like the duplication between >>>>> kvm_io_bus_write and kvm_io_bus_write_cookie. >>>>> >>>>> Can you make kvm_io_bus_write, and perhaps kvm_io_bus_read too, return >>>>> the cookie, and return -EINVAL here if the cookie is garbage? >>>> >>>> On second though---no need to return -EINVAL, you can just pass the >>>> cookie by value and tail-call kvm_io_bus_write. Whatever makes the s390 >>>> code look nicer. >>> >>> It would probably be easier to have the non-cookie functions call the >>> cookie functions with a negative cookie value, like the following >>> (untested): >> >> That would work too, but it adds a small overhead to the non-cookie >> calls. If Gleb agrees with you, it is fine; otherwise, I'd prefer that >> one explicitly requests the cookie on input. > > Just to compare, I also did a patch that returns the index instead > (equally untested). Changing the callers was straightforward; we gain > an extra scu_dereference() in the invalid cookie case.
This looks much nicer, thanks for putting up with me! Paolo > From ff45cdc27e47020251f0100759adf372c19a29c4 Mon Sep 17 00:00:00 2001 > From: Cornelia Huck <[email protected]> > Date: Tue, 2 Jul 2013 13:30:56 +0200 > Subject: [PATCH 1/2] KVM: kvm-io: support cookies > > Add new functions kvm_io_bus_{read,write}_cookie() that allows users of > the kvm io infrastructure to use a cookie value to speed up lookup of a > device on an io bus. > > kvm_io_bus_{read,write} now returns the index on the bus; existing callers > have been fixed up to accept return codes > 0. > > Signed-off-by: Cornelia Huck <[email protected]> > --- > arch/ia64/kvm/kvm-ia64.c | 2 +- > arch/powerpc/kvm/powerpc.c | 4 ++-- > arch/x86/kvm/x86.c | 8 ++++--- > include/linux/kvm_host.h | 4 ++++ > virt/kvm/kvm_main.c | 58 > +++++++++++++++++++++++++++++++++++++++++++++- > 5 files changed, 69 insertions(+), 7 deletions(-) > > diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c > index 5b2dc0d..465ab54 100644 > --- a/arch/ia64/kvm/kvm-ia64.c > +++ b/arch/ia64/kvm/kvm-ia64.c > @@ -250,7 +250,7 @@ mmio: > else > r = kvm_io_bus_write(vcpu->kvm, KVM_MMIO_BUS, p->addr, > p->size, &p->data); > - if (r) > + if (r < 0) > printk(KERN_ERR"kvm: No iodevice found! addr:%lx\n", p->addr); > p->state = STATE_IORESP_READY; > > diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c > index 6316ee3..26c44d0 100644 > --- a/arch/powerpc/kvm/powerpc.c > +++ b/arch/powerpc/kvm/powerpc.c > @@ -649,7 +649,7 @@ int kvmppc_handle_load(struct kvm_run *run, struct > kvm_vcpu *vcpu, > > srcu_read_unlock(&vcpu->kvm->srcu, idx); > > - if (!ret) { > + if (ret >= 0) { > kvmppc_complete_mmio_load(vcpu, run); > vcpu->mmio_needed = 0; > return EMULATE_DONE; > @@ -711,7 +711,7 @@ int kvmppc_handle_store(struct kvm_run *run, struct > kvm_vcpu *vcpu, > > srcu_read_unlock(&vcpu->kvm->srcu, idx); > > - if (!ret) { > + if (ret >= 0) { > vcpu->mmio_needed = 0; > return EMULATE_DONE; > } > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 7d71c0f..62b325c 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -3860,7 +3860,8 @@ static int vcpu_mmio_write(struct kvm_vcpu *vcpu, gpa_t > addr, int len, > n = min(len, 8); > if (!(vcpu->arch.apic && > !kvm_iodevice_write(&vcpu->arch.apic->dev, addr, n, v)) > - && kvm_io_bus_write(vcpu->kvm, KVM_MMIO_BUS, addr, n, v)) > + && (kvm_io_bus_write(vcpu->kvm, KVM_MMIO_BUS, addr, n, v) > + < 0)) > break; > handled += n; > addr += n; > @@ -3880,7 +3881,8 @@ static int vcpu_mmio_read(struct kvm_vcpu *vcpu, gpa_t > addr, int len, void *v) > n = min(len, 8); > if (!(vcpu->arch.apic && > !kvm_iodevice_read(&vcpu->arch.apic->dev, addr, n, v)) > - && kvm_io_bus_read(vcpu->kvm, KVM_MMIO_BUS, addr, n, v)) > + && (kvm_io_bus_read(vcpu->kvm, KVM_MMIO_BUS, addr, n, v) > + < 0)) > break; > trace_kvm_mmio(KVM_TRACE_MMIO_READ, n, addr, *(u64 *)v); > handled += n; > @@ -4361,7 +4363,7 @@ static int kernel_pio(struct kvm_vcpu *vcpu, void *pd) > r = kvm_io_bus_write(vcpu->kvm, KVM_PIO_BUS, > vcpu->arch.pio.port, vcpu->arch.pio.size, > pd); > - return r; > + return (r >= 0) ? 0 : r; > } > > static int emulator_pio_in_out(struct kvm_vcpu *vcpu, int size, > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index e3aae6d..60e261c9 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -159,8 +159,12 @@ enum kvm_bus { > > int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, > int len, const void *val); > +int kvm_io_bus_write_cookie(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t > addr, > + int len, const void *val, long cookie); > int kvm_io_bus_read(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, int > len, > void *val); > +int kvm_io_bus_read_cookie(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, > + int len, void *val, long cookie); > int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t > addr, > int len, struct kvm_io_device *dev); > int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx, > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 1580dd4..ed34f10 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -2884,13 +2884,41 @@ int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus > bus_idx, gpa_t addr, > while (idx < bus->dev_count && > kvm_io_bus_sort_cmp(&range, &bus->range[idx]) == 0) { > if (!kvm_iodevice_write(bus->range[idx].dev, addr, len, val)) > - return 0; > + return idx; > idx++; > } > > return -EOPNOTSUPP; > } > > +/* kvm_io_bus_write_cookie - called under kvm->slots_lock */ > +int kvm_io_bus_write_cookie(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t > addr, > + int len, const void *val, long cookie) > +{ > + struct kvm_io_bus *bus; > + struct kvm_io_range range; > + > + range = (struct kvm_io_range) { > + .addr = addr, > + .len = len, > + }; > + > + bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu); > + > + /* First try the device referenced by cookie. */ > + if ((cookie >= 0) && (cookie < bus->dev_count) && > + (kvm_io_bus_sort_cmp(&range, &bus->range[cookie]) == 0)) > + if (!kvm_iodevice_write(bus->range[cookie].dev, addr, len, > + val)) > + return cookie; > + > + /* > + * cookie contained garbage; fall back to search and return the > + * correct cookie value. > + */ > + return kvm_io_bus_write(kvm, bus_idx, addr, len, val); > +} > + > /* kvm_io_bus_read - called under kvm->slots_lock */ > int kvm_io_bus_read(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, > int len, void *val) > @@ -2919,6 +2947,34 @@ int kvm_io_bus_read(struct kvm *kvm, enum kvm_bus > bus_idx, gpa_t addr, > return -EOPNOTSUPP; > } > > +/* kvm_io_bus_read_cookie - called under kvm->slots_lock */ > +int kvm_io_bus_read_cookie(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, > + int len, void *val, long cookie) > +{ > + struct kvm_io_bus *bus; > + struct kvm_io_range range; > + > + range = (struct kvm_io_range) { > + .addr = addr, > + .len = len, > + }; > + > + bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu); > + > + /* First try the device referenced by cookie. */ > + if ((cookie >= 0) && (cookie < bus->dev_count) && > + (kvm_io_bus_sort_cmp(&range, &bus->range[cookie]) == 0)) > + if (!kvm_iodevice_read(bus->range[cookie].dev, addr, len, > + val)) > + return cookie; > + > + /* > + * cookie contained garbage; fall back to search and return the > + * correct cookie value. > + */ > + return kvm_io_bus_read(kvm, bus_idx, addr, len, val); > +} > + > /* Caller must hold slots_lock. */ > int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t > addr, > int len, struct kvm_io_device *dev) > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
