On Thu, 21 Feb 2013 18:34:59 +0200
"Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote:
> On Thu, Feb 21, 2013 at 04:21:43PM +0100, Cornelia Huck wrote:
> > On Thu, 21 Feb 2013 16:39:05 +0200
> > "Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote:
> >
> > > On Thu, Feb 21, 2013 at 02:13:00PM +0100, Cornelia Huck wrote:
> > > > As s390 doesn't use memory writes for virtio notifcations, create
> > > > a special kind of ioeventfd instead that hooks up into diagnose
> > > > 0x500 (kvm hypercall) with function code 3 (virtio-ccw notification).
> > > >
> > > > Signed-off-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
> > >
> > > Do we really have to put virtio specific stuff into kvm?
> > > How about we add generic functionality to match GPRs
> > > on a hypercall and signal an eventfd?
> >
> > Worth a try implementing that.
> >
> > >
> > > Also, it's a bit unfortunate that this doesn't use
> > > the io bus datastructure, long term the linked list handling
> > > might become a bottleneck, using shared code this could maybe
> > > benefit from performance optimizations there.
> >
> > The linked list stuff was more like an initial implementation that
> > could be improved later.
> >
> > > io bus data structure currently has the ability to match on
> > > two 64 bit fields (addr/datamatch) and a signed 32 bit one (length).
> > > Isn't this sufficient for your purposes?
> > > How about sticking subchannel id in address, vq in data match
> > > and using io bus?
> >
> > I can give that a try. (I must admit that I didn't look at the iobus
> > stuff in detail.)
> >
> > >
> > > BTW maybe we could do this for the user interface too,
> > > while I'm not 100% sure it's the cleanest thing to do
> > > (or will work), it would certainly minimize the patchset.
> >
> > You mean integrating with the generic interface and dropping the new
> > ARCH flag?
>
> Not sure about the flag but we could use the general structure
> without an arch-specific format, if that's a good fit.
>
So I have something that seems to do what I want. I'll see if I can
morph it into something presentable tomorrow.
diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig
index b58dd86..3c43e30 100644
--- a/arch/s390/kvm/Kconfig
+++ b/arch/s390/kvm/Kconfig
@@ -22,6 +22,7 @@ config KVM
select PREEMPT_NOTIFIERS
select ANON_INODES
select HAVE_KVM_CPU_RELAX_INTERCEPT
+ select HAVE_KVM_EVENTFD
---help---
Support hosting paravirtualized guest machines using the SIE
virtualization capability on the mainframe. This should work
diff --git a/arch/s390/kvm/Makefile b/arch/s390/kvm/Makefile
index 3975722..8fe9d65 100644
--- a/arch/s390/kvm/Makefile
+++ b/arch/s390/kvm/Makefile
@@ -6,7 +6,7 @@
# it under the terms of the GNU General Public License (version 2 only)
# as published by the Free Software Foundation.
-common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o)
+common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o eventfd.o)
ccflags-y := -Ivirt/kvm -Iarch/s390/kvm
diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c
index a390687..7fc195e 100644
--- a/arch/s390/kvm/diag.c
+++ b/arch/s390/kvm/diag.c
@@ -104,6 +104,20 @@ static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
return -EREMOTE;
}
+static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
+{
+ int ret, idx;
+ u64 vq = vcpu->run->s.regs.gprs[3];
+
+ idx = srcu_read_lock(&vcpu->kvm->srcu);
+ ret = kvm_io_bus_write(vcpu->kvm, KVM_CSS_BUS,
+ vcpu->run->s.regs.gprs[2],
+ vcpu->run->s.regs.gprs[1],
+ &vq);
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
+ return ret;
+}
+
int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
{
int code = (vcpu->arch.sie_block->ipb & 0xfff0000) >> 16;
@@ -118,6 +132,8 @@ int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
return __diag_time_slice_end_directed(vcpu);
case 0x308:
return __diag_ipl_functions(vcpu);
+ case 0x500:
+ return __diag_virtio_hypercall(vcpu);
default:
return -EOPNOTSUPP;
}
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index f822d36..04d2454 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -142,6 +142,7 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_ONE_REG:
case KVM_CAP_ENABLE_CAP:
case KVM_CAP_S390_CSS_SUPPORT:
+ case KVM_CAP_IOEVENTFD:
r = 1;
break;
case KVM_CAP_NR_VCPUS:
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 3b768ef..59be516 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -148,6 +148,7 @@ struct kvm_io_bus {
enum kvm_bus {
KVM_MMIO_BUS,
KVM_PIO_BUS,
+ KVM_CSS_BUS,
KVM_NR_BUSES
};
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 9a2db57..1df0766 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -448,12 +448,14 @@ enum {
kvm_ioeventfd_flag_nr_datamatch,
kvm_ioeventfd_flag_nr_pio,
kvm_ioeventfd_flag_nr_deassign,
+ kvm_ioeventfd_flag_nr_css,
kvm_ioeventfd_flag_nr_max,
};
#define KVM_IOEVENTFD_FLAG_DATAMATCH (1 << kvm_ioeventfd_flag_nr_datamatch)
#define KVM_IOEVENTFD_FLAG_PIO (1 << kvm_ioeventfd_flag_nr_pio)
#define KVM_IOEVENTFD_FLAG_DEASSIGN (1 << kvm_ioeventfd_flag_nr_deassign)
+#define KVM_IOEVENTFD_FLAG_CSS (1 << kvm_ioeventfd_flag_nr_css)
#define KVM_IOEVENTFD_VALID_FLAG_MASK ((1 << kvm_ioeventfd_flag_nr_max) - 1)
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index f0ced1a..57a06ff 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -576,6 +576,7 @@ struct _ioeventfd {
u64 datamatch;
struct kvm_io_device dev;
bool wildcard;
+ bool is_css;
};
static inline struct _ioeventfd *
@@ -607,24 +608,27 @@ ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
/* otherwise, we have to actually compare the data */
- BUG_ON(!IS_ALIGNED((unsigned long)val, len));
-
- switch (len) {
- case 1:
- _val = *(u8 *)val;
- break;
- case 2:
- _val = *(u16 *)val;
- break;
- case 4:
- _val = *(u32 *)val;
- break;
- case 8:
+ if (!p->is_css) {
+ BUG_ON(!IS_ALIGNED((unsigned long)val, len));
+
+ switch (len) {
+ case 1:
+ _val = *(u8 *)val;
+ break;
+ case 2:
+ _val = *(u16 *)val;
+ break;
+ case 4:
+ _val = *(u32 *)val;
+ break;
+ case 8:
+ _val = *(u64 *)val;
+ break;
+ default:
+ return false;
+ }
+ } else
_val = *(u64 *)val;
- break;
- default:
- return false;
- }
return _val == p->datamatch ? true : false;
}
@@ -679,25 +683,29 @@ static int
kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
{
int pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
- enum kvm_bus bus_idx = pio ? KVM_PIO_BUS : KVM_MMIO_BUS;
+ int css = args->flags & KVM_IOEVENTFD_FLAG_CSS;
+ enum kvm_bus bus_idx;
struct _ioeventfd *p;
struct eventfd_ctx *eventfd;
int ret;
- /* must be natural-word sized */
- switch (args->len) {
- case 1:
- case 2:
- case 4:
- case 8:
- break;
- default:
- return -EINVAL;
- }
+ bus_idx = pio ? KVM_PIO_BUS : css ? KVM_CSS_BUS: KVM_MMIO_BUS;
+ if (!css) {
+ /* must be natural-word sized */
+ switch (args->len) {
+ case 1:
+ case 2:
+ case 4:
+ case 8:
+ break;
+ default:
+ return -EINVAL;
+ }
- /* check for range overflow */
- if (args->addr + args->len < args->addr)
- return -EINVAL;
+ /* check for range overflow */
+ if (args->addr + args->len < args->addr)
+ return -EINVAL;
+ }
/* check for extra flags that we don't understand */
if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
@@ -717,6 +725,7 @@ kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
p->addr = args->addr;
p->length = args->len;
p->eventfd = eventfd;
+ p->is_css = css;
/* The datamatch feature is optional, otherwise this is a wildcard */
if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
@@ -759,11 +768,13 @@ static int
kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
{
int pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
- enum kvm_bus bus_idx = pio ? KVM_PIO_BUS : KVM_MMIO_BUS;
+ int css = args->flags & KVM_IOEVENTFD_FLAG_CSS;
+ enum kvm_bus bus_idx;
struct _ioeventfd *p, *tmp;
struct eventfd_ctx *eventfd;
int ret = -ENOENT;
+ bus_idx = pio ? KVM_PIO_BUS : css ? KVM_CSS_BUS: KVM_MMIO_BUS;
eventfd = eventfd_ctx_fdget(args->fd);
if (IS_ERR(eventfd))
return PTR_ERR(eventfd);
--
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