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): >From 12a6e9821f1a07ecd918e927a4049263ad6f1724 Mon Sep 17 00:00:00 2001 From: Cornelia Huck <[email protected]> Date: Tue, 2 Jul 2013 13:30:56 +0200 Subject: [PATCH] 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. Signed-off-by: Cornelia Huck <[email protected]> --- include/linux/kvm_host.h | 4 +++ virt/kvm/kvm_main.c | 82 ++++++++++++++++++++++++++++++++++++++---------- 2 files changed, 70 insertions(+), 16 deletions(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index e3aae6d..97849fc 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..21e6d7d 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2863,11 +2863,11 @@ static int kvm_io_bus_get_first_dev(struct kvm_io_bus *bus, return off; } -/* kvm_io_bus_write - called under kvm->slots_lock */ -int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, - int len, const void *val) +/* 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) { - int idx; + int idx, ret = -EOPNOTSUPP; struct kvm_io_bus *bus; struct kvm_io_range range; @@ -2877,25 +2877,50 @@ int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, }; 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 0; + + /* + * *cookie contained garbage; fall back to search and return the + * correct value in *cookie. + */ idx = kvm_io_bus_get_first_dev(bus, addr, len); if (idx < 0) - return -EOPNOTSUPP; + goto out; 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; + if (!kvm_iodevice_write(bus->range[idx].dev, addr, len, val)) { + ret = 0; + goto out; + } idx++; } + idx = -ENOENT; +out: + *cookie = idx; + return ret; +} + +/* kvm_io_bus_write - called under kvm->slots_lock */ +int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, + int len, const void *val) +{ + long tmp = -1; - return -EOPNOTSUPP; + return kvm_io_bus_write_cookie(kvm, bus_idx, addr, len, val, &tmp); } -/* 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) +/* 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) { - int idx; + int idx, ret = -EOPNOTSUPP; struct kvm_io_bus *bus; struct kvm_io_range range; @@ -2905,18 +2930,43 @@ int kvm_io_bus_read(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, }; 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 0; + + /* + * *cookie contained garbage; fall back to search and return the + * correct value in *cookie. + */ idx = kvm_io_bus_get_first_dev(bus, addr, len); if (idx < 0) - return -EOPNOTSUPP; + goto out; while (idx < bus->dev_count && kvm_io_bus_sort_cmp(&range, &bus->range[idx]) == 0) { - if (!kvm_iodevice_read(bus->range[idx].dev, addr, len, val)) - return 0; + if (!kvm_iodevice_read(bus->range[idx].dev, addr, len, val)) { + ret = 0; + goto out; + } idx++; } + idx = -ENOENT; +out: + *cookie = idx; + return ret; +} + +/* 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) +{ + long tmp = -1; - return -EOPNOTSUPP; + return kvm_io_bus_read_cookie(kvm, bus_idx, addr, len, val, &tmp); } /* Caller must hold slots_lock. */ -- 1.8.2.2 -- 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
