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* [PATCH 1/2] KVM: PPC: Book3S HV: XIVE: initialize private pointer when VPs are allocated
@ 2019-09-10 13:43 Greg Kurz
  2019-09-10 13:44 ` [PATCH 2/2] KVM: PPC: Book3S HV: XIVE: Set kvm->arch.xive " Greg Kurz
  0 siblings, 1 reply; 3+ messages in thread
From: Greg Kurz @ 2019-09-10 13:43 UTC (permalink / raw)
  To: Paul Mackerras; +Cc: David Gibson, Cédric Le Goater, kvm-ppc, kvm

From: Cédric Le Goater <clg@kaod.org>

Do not assign the device private pointer before making sure the XIVE
VPs are allocated in OPAL and test pointer validity when releasing
the device.

Fixes: 5422e95103cf ("KVM: PPC: Book3S HV: XIVE: Replace the 'destroy' method by a 'release' method")
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Greg Kurz <groug@kaod.org>
---
 arch/powerpc/kvm/book3s_xive.c        |   13 +++++++++++--
 arch/powerpc/kvm/book3s_xive_native.c |   13 +++++++++++--
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
index 591bfb4bfd0f..cd2006bfcd3e 100644
--- a/arch/powerpc/kvm/book3s_xive.c
+++ b/arch/powerpc/kvm/book3s_xive.c
@@ -1897,12 +1897,21 @@ void kvmppc_xive_free_sources(struct kvmppc_xive_src_block *sb)
 static void kvmppc_xive_release(struct kvm_device *dev)
 {
 	struct kvmppc_xive *xive = dev->private;
-	struct kvm *kvm = xive->kvm;
+	struct kvm *kvm;
 	struct kvm_vcpu *vcpu;
 	int i;
 
 	pr_devel("Releasing xive device\n");
 
+	/*
+	 * In case of failure (OPAL) at device creation, the device
+	 * can be partially initialized.
+	 */
+	if (!xive)
+		return;
+
+	kvm = xive->kvm;
+
 	/*
 	 * Since this is the device release function, we know that
 	 * userspace does not have any open fd referring to the
@@ -2001,7 +2010,6 @@ static int kvmppc_xive_create(struct kvm_device *dev, u32 type)
 	if (!xive)
 		return -ENOMEM;
 
-	dev->private = xive;
 	xive->dev = dev;
 	xive->kvm = kvm;
 	mutex_init(&xive->lock);
@@ -2031,6 +2039,7 @@ static int kvmppc_xive_create(struct kvm_device *dev, u32 type)
 	if (ret)
 		return ret;
 
+	dev->private = xive;
 	return 0;
 }
 
diff --git a/arch/powerpc/kvm/book3s_xive_native.c b/arch/powerpc/kvm/book3s_xive_native.c
index 248c1ea9e788..e9cbb42de424 100644
--- a/arch/powerpc/kvm/book3s_xive_native.c
+++ b/arch/powerpc/kvm/book3s_xive_native.c
@@ -987,12 +987,21 @@ static int kvmppc_xive_native_has_attr(struct kvm_device *dev,
 static void kvmppc_xive_native_release(struct kvm_device *dev)
 {
 	struct kvmppc_xive *xive = dev->private;
-	struct kvm *kvm = xive->kvm;
+	struct kvm *kvm;
 	struct kvm_vcpu *vcpu;
 	int i;
 
 	pr_devel("Releasing xive native device\n");
 
+	/*
+	 * In case of failure (OPAL) at device creation, the device
+	 * can be partially initialized.
+	 */
+	if (!xive)
+		return;
+
+	kvm = xive->kvm;
+
 	/*
 	 * Clear the KVM device file address_space which is used to
 	 * unmap the ESB pages when a device is passed-through.
@@ -1076,7 +1085,6 @@ static int kvmppc_xive_native_create(struct kvm_device *dev, u32 type)
 	if (!xive)
 		return -ENOMEM;
 
-	dev->private = xive;
 	xive->dev = dev;
 	xive->kvm = kvm;
 	kvm->arch.xive = xive;
@@ -1100,6 +1108,7 @@ static int kvmppc_xive_native_create(struct kvm_device *dev, u32 type)
 	if (ret)
 		return ret;
 
+	dev->private = xive;
 	return 0;
 }
 


^ permalink raw reply	[flat|nested] 3+ messages in thread

* [PATCH 2/2] KVM: PPC: Book3S HV: XIVE: Set kvm->arch.xive when VPs are allocated
  2019-09-10 13:43 [PATCH 1/2] KVM: PPC: Book3S HV: XIVE: initialize private pointer when VPs are allocated Greg Kurz
@ 2019-09-10 13:44 ` " Greg Kurz
  2019-09-10 13:49   ` Cédric Le Goater
  0 siblings, 1 reply; 3+ messages in thread
From: Greg Kurz @ 2019-09-10 13:44 UTC (permalink / raw)
  To: Paul Mackerras; +Cc: David Gibson, Cédric Le Goater, kvm-ppc, kvm

If we cannot allocate the XIVE VPs in OPAL, the creation of a XIVE or
XICS-on-XIVE device is aborted as expected, but we leave kvm->arch.xive
set forever since the relase method isn't called in this case. Any
subsequent tentative to create a XIVE or XICS-on-XIVE for this VM will
thus always fail. This is a problem for QEMU since it destroys and
re-creates these devices when the VM is reset: the VM would be
restricted to using the emulated XIVE or XICS forever.

As an alternative to adding rollback, do not assign kvm->arch.xive before
making sure the XIVE VPs are allocated in OPAL.

Fixes: 5422e95103cf ("KVM: PPC: Book3S HV: XIVE: Replace the 'destroy' method by a 'release' method")
Signed-off-by: Greg Kurz <groug@kaod.org>
---
 arch/powerpc/kvm/book3s_xive.c        |   11 +++++------
 arch/powerpc/kvm/book3s_xive_native.c |    2 +-
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
index cd2006bfcd3e..2ef43d037a4f 100644
--- a/arch/powerpc/kvm/book3s_xive.c
+++ b/arch/powerpc/kvm/book3s_xive.c
@@ -2006,6 +2006,10 @@ static int kvmppc_xive_create(struct kvm_device *dev, u32 type)
 
 	pr_devel("Creating xive for partition\n");
 
+	/* Already there ? */
+	if (kvm->arch.xive)
+		return -EEXIST;
+
 	xive = kvmppc_xive_get_device(kvm, type);
 	if (!xive)
 		return -ENOMEM;
@@ -2014,12 +2018,6 @@ static int kvmppc_xive_create(struct kvm_device *dev, u32 type)
 	xive->kvm = kvm;
 	mutex_init(&xive->lock);
 
-	/* Already there ? */
-	if (kvm->arch.xive)
-		ret = -EEXIST;
-	else
-		kvm->arch.xive = xive;
-
 	/* We use the default queue size set by the host */
 	xive->q_order = xive_native_default_eq_shift();
 	if (xive->q_order < PAGE_SHIFT)
@@ -2040,6 +2038,7 @@ static int kvmppc_xive_create(struct kvm_device *dev, u32 type)
 		return ret;
 
 	dev->private = xive;
+	kvm->arch.xive = xive;
 	return 0;
 }
 
diff --git a/arch/powerpc/kvm/book3s_xive_native.c b/arch/powerpc/kvm/book3s_xive_native.c
index e9cbb42de424..84a354b90f60 100644
--- a/arch/powerpc/kvm/book3s_xive_native.c
+++ b/arch/powerpc/kvm/book3s_xive_native.c
@@ -1087,7 +1087,6 @@ static int kvmppc_xive_native_create(struct kvm_device *dev, u32 type)
 
 	xive->dev = dev;
 	xive->kvm = kvm;
-	kvm->arch.xive = xive;
 	mutex_init(&xive->mapping_lock);
 	mutex_init(&xive->lock);
 
@@ -1109,6 +1108,7 @@ static int kvmppc_xive_native_create(struct kvm_device *dev, u32 type)
 		return ret;
 
 	dev->private = xive;
+	kvm->arch.xive = xive;
 	return 0;
 }
 


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH 2/2] KVM: PPC: Book3S HV: XIVE: Set kvm->arch.xive when VPs are allocated
  2019-09-10 13:44 ` [PATCH 2/2] KVM: PPC: Book3S HV: XIVE: Set kvm->arch.xive " Greg Kurz
@ 2019-09-10 13:49   ` Cédric Le Goater
  0 siblings, 0 replies; 3+ messages in thread
From: Cédric Le Goater @ 2019-09-10 13:49 UTC (permalink / raw)
  To: Greg Kurz, Paul Mackerras; +Cc: David Gibson, kvm-ppc, kvm

On 10/09/2019 15:44, Greg Kurz wrote:
> If we cannot allocate the XIVE VPs in OPAL, the creation of a XIVE or
> XICS-on-XIVE device is aborted as expected, but we leave kvm->arch.xive
> set forever since the relase method isn't called in this case. Any
> subsequent tentative to create a XIVE or XICS-on-XIVE for this VM will
> thus always fail. This is a problem for QEMU since it destroys and
> re-creates these devices when the VM is reset: the VM would be
> restricted to using the emulated XIVE or XICS forever.
> 
> As an alternative to adding rollback, do not assign kvm->arch.xive before
> making sure the XIVE VPs are allocated in OPAL.
> 
> Fixes: 5422e95103cf ("KVM: PPC: Book3S HV: XIVE: Replace the 'destroy' method by a 'release' method")
> Signed-off-by: Greg Kurz <groug@kaod.org>


Reviewed-by: Cédric Le Goater <clg@kaod.org>

Thanks,

C.

> ---
>  arch/powerpc/kvm/book3s_xive.c        |   11 +++++------
>  arch/powerpc/kvm/book3s_xive_native.c |    2 +-
>  2 files changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
> index cd2006bfcd3e..2ef43d037a4f 100644
> --- a/arch/powerpc/kvm/book3s_xive.c
> +++ b/arch/powerpc/kvm/book3s_xive.c
> @@ -2006,6 +2006,10 @@ static int kvmppc_xive_create(struct kvm_device *dev, u32 type)
>  
>  	pr_devel("Creating xive for partition\n");
>  
> +	/* Already there ? */
> +	if (kvm->arch.xive)
> +		return -EEXIST;
> +
>  	xive = kvmppc_xive_get_device(kvm, type);
>  	if (!xive)
>  		return -ENOMEM;
> @@ -2014,12 +2018,6 @@ static int kvmppc_xive_create(struct kvm_device *dev, u32 type)
>  	xive->kvm = kvm;
>  	mutex_init(&xive->lock);
>  
> -	/* Already there ? */
> -	if (kvm->arch.xive)
> -		ret = -EEXIST;
> -	else
> -		kvm->arch.xive = xive;
> -
>  	/* We use the default queue size set by the host */
>  	xive->q_order = xive_native_default_eq_shift();
>  	if (xive->q_order < PAGE_SHIFT)
> @@ -2040,6 +2038,7 @@ static int kvmppc_xive_create(struct kvm_device *dev, u32 type)
>  		return ret;
>  
>  	dev->private = xive;
> +	kvm->arch.xive = xive;
>  	return 0;
>  }
>  
> diff --git a/arch/powerpc/kvm/book3s_xive_native.c b/arch/powerpc/kvm/book3s_xive_native.c
> index e9cbb42de424..84a354b90f60 100644
> --- a/arch/powerpc/kvm/book3s_xive_native.c
> +++ b/arch/powerpc/kvm/book3s_xive_native.c
> @@ -1087,7 +1087,6 @@ static int kvmppc_xive_native_create(struct kvm_device *dev, u32 type)
>  
>  	xive->dev = dev;
>  	xive->kvm = kvm;
> -	kvm->arch.xive = xive;
>  	mutex_init(&xive->mapping_lock);
>  	mutex_init(&xive->lock);
>  
> @@ -1109,6 +1108,7 @@ static int kvmppc_xive_native_create(struct kvm_device *dev, u32 type)
>  		return ret;
>  
>  	dev->private = xive;
> +	kvm->arch.xive = xive;
>  	return 0;
>  }
>  
> 


^ permalink raw reply	[flat|nested] 3+ messages in thread

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2019-09-10 13:43 [PATCH 1/2] KVM: PPC: Book3S HV: XIVE: initialize private pointer when VPs are allocated Greg Kurz
2019-09-10 13:44 ` [PATCH 2/2] KVM: PPC: Book3S HV: XIVE: Set kvm->arch.xive " Greg Kurz
2019-09-10 13:49   ` Cédric Le Goater

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