Re: [PATCH v3 04/14] iommu/ioasid: Support setting system-wide capacity

[Jean-Philippe Brucker]

On Mon, Sep 28, 2020 at 02:38:31PM -0700, Jacob Pan wrote:
> IOASID is a system-wide resource that could vary on different systems.
> The default capacity is 20 bits as defined in the PCI-E specifications.
> This patch adds a function to allow adjusting system IOASID capacity.
> For VT-d this is set during boot as part of the Intel IOMMU
> initialization.
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>

Reviewed-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>

> ---
>  drivers/iommu/intel/iommu.c |  5 +++++
>  drivers/iommu/ioasid.c      | 20 ++++++++++++++++++++
>  include/linux/ioasid.h      | 11 +++++++++++
>  3 files changed, 36 insertions(+)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 18ed3b3c70d7..e7bcb299e51e 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -42,6 +42,7 @@
>  #include <linux/crash_dump.h>
>  #include <linux/numa.h>
>  #include <linux/swiotlb.h>
> +#include <linux/ioasid.h>

(not in alphabetical order)

>  #include <asm/irq_remapping.h>
>  #include <asm/cacheflush.h>
>  #include <asm/iommu.h>
> @@ -3331,6 +3332,10 @@ static int __init init_dmars(void)
>  	if (ret)
>  		goto free_iommu;
>  
> +	/* PASID is needed for scalable mode irrespective to SVM */
> +	if (intel_iommu_sm)
> +		ioasid_install_capacity(intel_pasid_max_id);
> +
>  	/*
>  	 * for each drhd
>  	 *   enable fault log
> diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c
> index 6cfbdfb492e0..4277cb17e15b 100644
> --- a/drivers/iommu/ioasid.c
> +++ b/drivers/iommu/ioasid.c
> @@ -10,6 +10,10 @@
>  #include <linux/spinlock.h>
>  #include <linux/xarray.h>
>  
> +/* Default to PCIe standard 20 bit PASID */
> +#define PCI_PASID_MAX 0x100000
> +static ioasid_t ioasid_capacity = PCI_PASID_MAX;
> +static ioasid_t ioasid_capacity_avail = PCI_PASID_MAX;
>  struct ioasid_data {
>  	ioasid_t id;
>  	struct ioasid_set *set;
> @@ -17,6 +21,22 @@ struct ioasid_data {
>  	struct rcu_head rcu;
>  };
>  
> +void ioasid_install_capacity(ioasid_t total)
> +{
> +	if (ioasid_capacity && ioasid_capacity != PCI_PASID_MAX) {
> +		pr_warn("IOASID capacity is already set.\n");
> +		return;
> +	}
> +	ioasid_capacity = ioasid_capacity_avail = total;
> +}
> +EXPORT_SYMBOL_GPL(ioasid_install_capacity);
> +
> +ioasid_t ioasid_get_capacity(void)
> +{
> +	return ioasid_capacity;
> +}
> +EXPORT_SYMBOL_GPL(ioasid_get_capacity);
> +
>  /*
>   * struct ioasid_allocator_data - Internal data structure to hold information
>   * about an allocator. There are two types of allocators:
> diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h
> index c7f649fa970a..7fc320656be2 100644
> --- a/include/linux/ioasid.h
> +++ b/include/linux/ioasid.h
> @@ -32,6 +32,8 @@ struct ioasid_allocator_ops {
>  #define DECLARE_IOASID_SET(name) struct ioasid_set name = { 0 }
>  
>  #if IS_ENABLED(CONFIG_IOASID)
> +void ioasid_install_capacity(ioasid_t total);
> +ioasid_t ioasid_get_capacity(void);
>  ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max,
>  		      void *private);
>  void ioasid_free(ioasid_t ioasid);
> @@ -42,6 +44,15 @@ void ioasid_unregister_allocator(struct ioasid_allocator_ops *allocator);
>  int ioasid_attach_data(ioasid_t ioasid, void *data);
>  void ioasid_detach_data(ioasid_t ioasid);
>  #else /* !CONFIG_IOASID */
> +static inline void ioasid_install_capacity(ioasid_t total)
> +{
> +}
> +
> +static inline ioasid_t ioasid_get_capacity(void)
> +{
> +	return 0;
> +}
> +
>  static inline ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min,
>  				    ioasid_t max, void *private)
>  {
> -- 
> 2.7.4
>