diff mbox series

[2/2] PCI: iproc: Support multi-MSI only on uniprocessor kernel

Message ID 20210606123044.31250-2-sbodomerle@gmail.com (mailing list archive)
State New
Delegated to: Lorenzo Pieralisi
Headers show
Series [1/2] PCI: iproc: fix the base vector number allocation for multi-MSI | expand

Commit Message

Sandor Bodo-Merle June 6, 2021, 12:30 p.m. UTC
The interrupt affinity scheme used by this driver is incompatible with
multi-MSI as it implies moving the doorbell address to that of another MSI
group.  This isn't possible for multi-MSI, as all the MSIs must have the
same doorbell address. As such it is restricted to systems with a single
CPU.

Fixes: fc54bae28818 ("PCI: iproc: Allow allocation of multiple MSIs")
Reported-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Sandor Bodo-Merle <sbodomerle@gmail.com>
---
 drivers/pci/controller/pcie-iproc-msi.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Comments

Marc Zyngier June 6, 2021, 1:28 p.m. UTC | #1
On 2021-06-06 13:30, Sandor Bodo-Merle wrote:
> The interrupt affinity scheme used by this driver is incompatible with
> multi-MSI as it implies moving the doorbell address to that of another 
> MSI
> group.  This isn't possible for multi-MSI, as all the MSIs must have 
> the
> same doorbell address. As such it is restricted to systems with a 
> single
> CPU.
> 
> Fixes: fc54bae28818 ("PCI: iproc: Allow allocation of multiple MSIs")
> Reported-by: Marc Zyngier <maz@kernel.org>
> Signed-off-by: Sandor Bodo-Merle <sbodomerle@gmail.com>

Acked-by: Marc Zyngier <maz@kernel.org>

         M.
Ray Jui June 7, 2021, 4:48 p.m. UTC | #2
On 6/6/2021 5:30 AM, Sandor Bodo-Merle wrote:
> The interrupt affinity scheme used by this driver is incompatible with
> multi-MSI as it implies moving the doorbell address to that of another MSI
> group.  This isn't possible for multi-MSI, as all the MSIs must have the
> same doorbell address. As such it is restricted to systems with a single
> CPU.
> 
> Fixes: fc54bae28818 ("PCI: iproc: Allow allocation of multiple MSIs")
> Reported-by: Marc Zyngier <maz@kernel.org>
> Signed-off-by: Sandor Bodo-Merle <sbodomerle@gmail.com>
> ---
>  drivers/pci/controller/pcie-iproc-msi.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/pcie-iproc-msi.c b/drivers/pci/controller/pcie-iproc-msi.c
> index 557d93dcb3bc..81b4effeb130 100644
> --- a/drivers/pci/controller/pcie-iproc-msi.c
> +++ b/drivers/pci/controller/pcie-iproc-msi.c
> @@ -171,7 +171,7 @@ static struct irq_chip iproc_msi_irq_chip = {
>  
>  static struct msi_domain_info iproc_msi_domain_info = {
>  	.flags = MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
> -		MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX,
> +		MSI_FLAG_PCI_MSIX,
>  	.chip = &iproc_msi_irq_chip,
>  };
>  
> @@ -250,6 +250,9 @@ static int iproc_msi_irq_domain_alloc(struct irq_domain *domain,
>  	struct iproc_msi *msi = domain->host_data;
>  	int hwirq, i;
>  
> +	if (msi->nr_cpus > 1 && nr_irqs > 1)
> +		return -EINVAL;
> +

This should never happen since the framework would have guarded against
this. But I guess it does not hurt to have the check here.

>  	mutex_lock(&msi->bitmap_lock);
>  
>  	/*
> @@ -540,6 +543,9 @@ int iproc_msi_init(struct iproc_pcie *pcie, struct device_node *node)
>  	mutex_init(&msi->bitmap_lock);
>  	msi->nr_cpus = num_possible_cpus();
>  
> +	if (msi->nr_cpus == 1)
> +		iproc_msi_domain_info.flags |=  MSI_FLAG_MULTI_PCI_MSI;
> +
>  	msi->nr_irqs = of_irq_count(node);
>  	if (!msi->nr_irqs) {
>  		dev_err(pcie->dev, "found no MSI GIC interrupt\n");
> 

Looks fine to me. Thanks.

Acked-by: Ray Jui <ray.jui@broadcom.com>
Pali Rohár June 7, 2021, 9:18 p.m. UTC | #3
On Monday 07 June 2021 09:48:21 Ray Jui wrote:
> On 6/6/2021 5:30 AM, Sandor Bodo-Merle wrote:
> > The interrupt affinity scheme used by this driver is incompatible with
> > multi-MSI as it implies moving the doorbell address to that of another MSI
> > group.  This isn't possible for multi-MSI, as all the MSIs must have the
> > same doorbell address. As such it is restricted to systems with a single
> > CPU.
> > 
> > Fixes: fc54bae28818 ("PCI: iproc: Allow allocation of multiple MSIs")
> > Reported-by: Marc Zyngier <maz@kernel.org>
> > Signed-off-by: Sandor Bodo-Merle <sbodomerle@gmail.com>
> > ---
> >  drivers/pci/controller/pcie-iproc-msi.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/pci/controller/pcie-iproc-msi.c b/drivers/pci/controller/pcie-iproc-msi.c
> > index 557d93dcb3bc..81b4effeb130 100644
> > --- a/drivers/pci/controller/pcie-iproc-msi.c
> > +++ b/drivers/pci/controller/pcie-iproc-msi.c
> > @@ -171,7 +171,7 @@ static struct irq_chip iproc_msi_irq_chip = {
> >  
> >  static struct msi_domain_info iproc_msi_domain_info = {
> >  	.flags = MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
> > -		MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX,
> > +		MSI_FLAG_PCI_MSIX,
> >  	.chip = &iproc_msi_irq_chip,
> >  };
> >  
> > @@ -250,6 +250,9 @@ static int iproc_msi_irq_domain_alloc(struct irq_domain *domain,
> >  	struct iproc_msi *msi = domain->host_data;
> >  	int hwirq, i;
> >  
> > +	if (msi->nr_cpus > 1 && nr_irqs > 1)
> > +		return -EINVAL;
> > +
> 
> This should never happen since the framework would have guarded against
> this. But I guess it does not hurt to have the check here.

Yes, this should not happen, but I suggested to add a comment or assert
or some other way to document this kind of constrain. Lot of times code
is copy+pasted to new drivers and because only this one driver has
.alloc function which is using nr_cpus for allocating msi bitmap, it
really makes sense to document this constrain also explicitly.

> >  	mutex_lock(&msi->bitmap_lock);
> >  
> >  	/*
> > @@ -540,6 +543,9 @@ int iproc_msi_init(struct iproc_pcie *pcie, struct device_node *node)
> >  	mutex_init(&msi->bitmap_lock);
> >  	msi->nr_cpus = num_possible_cpus();
> >  
> > +	if (msi->nr_cpus == 1)
> > +		iproc_msi_domain_info.flags |=  MSI_FLAG_MULTI_PCI_MSI;
                                              ^^
Just a small note: there are two spaces instead of just one

Otherwise looks good to me:

Acked-by: Pali Rohár <pali@kernel.org>

> > +
> >  	msi->nr_irqs = of_irq_count(node);
> >  	if (!msi->nr_irqs) {
> >  		dev_err(pcie->dev, "found no MSI GIC interrupt\n");
> > 
> 
> Looks fine to me. Thanks.
> 
> Acked-by: Ray Jui <ray.jui@broadcom.com>
Lorenzo Pieralisi June 21, 2021, 2:47 p.m. UTC | #4
On Sun, Jun 06, 2021 at 02:30:44PM +0200, Sandor Bodo-Merle wrote:
> The interrupt affinity scheme used by this driver is incompatible with
> multi-MSI as it implies moving the doorbell address to that of another MSI
> group.  This isn't possible for multi-MSI, as all the MSIs must have the
> same doorbell address. As such it is restricted to systems with a single
> CPU.
> 
> Fixes: fc54bae28818 ("PCI: iproc: Allow allocation of multiple MSIs")
> Reported-by: Marc Zyngier <maz@kernel.org>
> Signed-off-by: Sandor Bodo-Merle <sbodomerle@gmail.com>
> ---
>  drivers/pci/controller/pcie-iproc-msi.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)

Can you just resend the series with the very minor changes requested
fixed please ?

Please carry/apply the review tags as well.

Thanks,
Lorenzo

> diff --git a/drivers/pci/controller/pcie-iproc-msi.c b/drivers/pci/controller/pcie-iproc-msi.c
> index 557d93dcb3bc..81b4effeb130 100644
> --- a/drivers/pci/controller/pcie-iproc-msi.c
> +++ b/drivers/pci/controller/pcie-iproc-msi.c
> @@ -171,7 +171,7 @@ static struct irq_chip iproc_msi_irq_chip = {
>  
>  static struct msi_domain_info iproc_msi_domain_info = {
>  	.flags = MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
> -		MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX,
> +		MSI_FLAG_PCI_MSIX,
>  	.chip = &iproc_msi_irq_chip,
>  };
>  
> @@ -250,6 +250,9 @@ static int iproc_msi_irq_domain_alloc(struct irq_domain *domain,
>  	struct iproc_msi *msi = domain->host_data;
>  	int hwirq, i;
>  
> +	if (msi->nr_cpus > 1 && nr_irqs > 1)
> +		return -EINVAL;
> +
>  	mutex_lock(&msi->bitmap_lock);
>  
>  	/*
> @@ -540,6 +543,9 @@ int iproc_msi_init(struct iproc_pcie *pcie, struct device_node *node)
>  	mutex_init(&msi->bitmap_lock);
>  	msi->nr_cpus = num_possible_cpus();
>  
> +	if (msi->nr_cpus == 1)
> +		iproc_msi_domain_info.flags |=  MSI_FLAG_MULTI_PCI_MSI;
> +
>  	msi->nr_irqs = of_irq_count(node);
>  	if (!msi->nr_irqs) {
>  		dev_err(pcie->dev, "found no MSI GIC interrupt\n");
> -- 
> 2.31.0
>
diff mbox series

Patch

diff --git a/drivers/pci/controller/pcie-iproc-msi.c b/drivers/pci/controller/pcie-iproc-msi.c
index 557d93dcb3bc..81b4effeb130 100644
--- a/drivers/pci/controller/pcie-iproc-msi.c
+++ b/drivers/pci/controller/pcie-iproc-msi.c
@@ -171,7 +171,7 @@  static struct irq_chip iproc_msi_irq_chip = {
 
 static struct msi_domain_info iproc_msi_domain_info = {
 	.flags = MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
-		MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX,
+		MSI_FLAG_PCI_MSIX,
 	.chip = &iproc_msi_irq_chip,
 };
 
@@ -250,6 +250,9 @@  static int iproc_msi_irq_domain_alloc(struct irq_domain *domain,
 	struct iproc_msi *msi = domain->host_data;
 	int hwirq, i;
 
+	if (msi->nr_cpus > 1 && nr_irqs > 1)
+		return -EINVAL;
+
 	mutex_lock(&msi->bitmap_lock);
 
 	/*
@@ -540,6 +543,9 @@  int iproc_msi_init(struct iproc_pcie *pcie, struct device_node *node)
 	mutex_init(&msi->bitmap_lock);
 	msi->nr_cpus = num_possible_cpus();
 
+	if (msi->nr_cpus == 1)
+		iproc_msi_domain_info.flags |=  MSI_FLAG_MULTI_PCI_MSI;
+
 	msi->nr_irqs = of_irq_count(node);
 	if (!msi->nr_irqs) {
 		dev_err(pcie->dev, "found no MSI GIC interrupt\n");