[PATCH v2 0/2] KVM: ioeventfd cookies

[PATCH v2 0/2] KVM: ioeventfd cookies

[Cornelia Huck]

Hi,

here's the second version of the ioeventfd cookies support. Changes:

- provide kvm_io_bus_read_cookie as well
- refactoring of the cookie code in kvm_main.c
- adapt callers to changes

Cornelia Huck (2):
  KVM: kvm-io: support cookies
  KVM: s390: use cookies for ioeventfd

 arch/ia64/kvm/kvm-ia64.c   |  2 +-
 arch/powerpc/kvm/powerpc.c |  4 ++--
 arch/s390/kvm/diag.c       | 15 +++++++++---
 arch/x86/kvm/x86.c         |  8 ++++---
 include/linux/kvm_host.h   |  4 ++++
 virt/kvm/kvm_main.c        | 58 +++++++++++++++++++++++++++++++++++++++++++++-
 6 files changed, 81 insertions(+), 10 deletions(-)

-- 
1.8.2.2

[PATCH v2 1/2] KVM: kvm-io: support cookies

[Cornelia Huck]

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 <cornelia.huck@de.ibm.com>
---
 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)
-- 
1.8.2.2

[PATCH v2 2/2] KVM: s390: use cookies for ioeventfd

[Cornelia Huck]

Make use of cookies for the virtio ccw notification hypercall to speed up
lookup of devices on the io bus.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 arch/s390/kvm/diag.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c
index 3074475..e88c76e 100644
--- a/arch/s390/kvm/diag.c
+++ b/arch/s390/kvm/diag.c
@@ -119,11 +119,20 @@ static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
 	 * The layout is as follows:
 	 * - gpr 2 contains the subchannel id (passed as addr)
 	 * - gpr 3 contains the virtqueue index (passed as datamatch)
+	 * - gpr 4 contains the index on the bus (optionally)
 	 */
-	ret = kvm_io_bus_write(vcpu->kvm, KVM_VIRTIO_CCW_NOTIFY_BUS,
-				vcpu->run->s.regs.gprs[2],
-				8, &vcpu->run->s.regs.gprs[3]);
+	ret = kvm_io_bus_write_cookie(vcpu->kvm, KVM_VIRTIO_CCW_NOTIFY_BUS,
+				      vcpu->run->s.regs.gprs[2],
+				      8, &vcpu->run->s.regs.gprs[3],
+				      vcpu->run->s.regs.gprs[4]);
 	srcu_read_unlock(&vcpu->kvm->srcu, idx);
+
+	/*
+	 * Return cookie in gpr 2, but don't overwrite the register if the
+	 * diagnose will be handled by userspace.
+	 */
+	if (ret != -EOPNOTSUPP)
+		vcpu->run->s.regs.gprs[2] = ret;
 	/* kvm_io_bus_write returns -EOPNOTSUPP if it found no match. */
 	return ret < 0 ? ret : 0;
 }
-- 
1.8.2.2

Re: [PATCH v2 1/2] KVM: kvm-io: support cookies

[Gleb Natapov]

On Wed, Jul 03, 2013 at 02:48:35PM +0200, Cornelia Huck wrote:
> 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 <cornelia.huck@de.ibm.com>
> ---
>  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))
Better to go over 80 characters then break the line like that.

>  			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++;
Do not see the same change for kvm_io_bus_read().

>  	}
>  
>  	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);
I would refactor code a little bit to avoid calling srcu_dereference
twice and avoid changing kvm_io_bus_write() return semantics:

add __kvm_io_bus_write() functions that gets range and bus as
parameters, call it here and from kvm_io_bus_write(). Same for the
read.

> +
> +	/* 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)
> -- 
> 1.8.2.2

--
			Gleb.