Subject: [PATCH v2 23/23] [HACK] xen/arm: implement xen_remap_domain_mfn_range

From: [email-masked] (Konrad Rzeszutek Wilk)
Date: Tue, 7 Aug 2012 14:39:26 -0400

On Mon, Aug 06, 2012 at 03:27:26PM +0100, Stefano Stabellini wrote:
> From: Ian Campbell <[email-masked]>
> 
> Do not apply!

OK.
> 
> This is a simple, hacky implementation of xen_remap_domain_mfn_range,
> using XENMAPSPACE_gmfn_foreign.
> 
> It should use same interface as hybrid x86.

Yeah, Mukesh - can you share your patch here please?
> 
> Changes in v2:
> 
> - retain binary compatibility in xen_add_to_physmap: use a union.
> 
> Signed-off-by: Ian Campbell <[email-masked]>
> Signed-off-by: Stefano Stabellini <[email-masked]>
> ---
>  arch/arm/xen/enlighten.c       |   79 +++++++++++++++++++++++++++++++++++++++-
>  drivers/xen/privcmd.c          |   16 +++++----
>  drivers/xen/xenfs/super.c      |    7 ++++
>  include/xen/interface/memory.h |   15 ++++++--
>  4 files changed, 105 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
> index c244583..20ca1e4 100644
> --- a/arch/arm/xen/enlighten.c
> +++ b/arch/arm/xen/enlighten.c
> @@ -16,6 +16,10 @@
>  #include <linux/of.h>
>  #include <linux/of_irq.h>
>  #include <linux/of_address.h>
> +#include <linux/mm.h>
> +#include <linux/ioport.h>
> +
> +#include <asm/pgtable.h>
>  
>  struct start_info _xen_start_info;
>  struct start_info *xen_start_info = &_xen_start_info;
> @@ -38,12 +42,85 @@ EXPORT_SYMBOL_GPL(xen_platform_pci_unplug);
>  
>  static __read_mostly int xen_events_irq = -1;
>  
> +#define FOREIGN_MAP_BUFFER 0x90000000UL
> +#define FOREIGN_MAP_BUFFER_SIZE 0x10000000UL
> +struct resource foreign_map_resource = {
> +	.start = FOREIGN_MAP_BUFFER,
> +	.end = FOREIGN_MAP_BUFFER + FOREIGN_MAP_BUFFER_SIZE,
> +	.name = "Xen foreign map buffer",
> +	.flags = 0,
> +};
> +
> +static unsigned long foreign_map_buffer_pfn = FOREIGN_MAP_BUFFER >> PAGE_SHIFT;
> +
> +struct remap_data {
> +	struct mm_struct *mm;
> +	unsigned long mfn;
> +	pgprot_t prot;
> +};
> +
> +static int remap_area_mfn_pte_fn(pte_t *ptep, pgtable_t token,
> +				 unsigned long addr, void *data)
> +{
> +	struct remap_data *rmd = data;
> +	pte_t pte = pfn_pte(rmd->mfn, rmd->prot);
> +
> +	if (rmd->mfn < 0x90010)
> +		pr_crit("%s: ptep %p addr %#lx => %#x / %#lx\n",
> +		       __func__, ptep, addr, pte_val(pte), rmd->mfn);
> +
> +	set_pte_at(rmd->mm, addr, ptep, pte);
> +
> +	rmd->mfn++;
> +	return 0;
> +}
> +
>  int xen_remap_domain_mfn_range(struct vm_area_struct *vma,
>  			       unsigned long addr,
>  			       unsigned long mfn, int nr,
>  			       pgprot_t prot, unsigned domid)
>  {
> -	return -ENOSYS;
> +	int i, rc = 0;
> +	struct remap_data rmd = {
> +		.mm = vma->vm_mm,
> +		.prot = prot,
> +	};
> +	struct xen_add_to_physmap xatp = {
> +		.domid = DOMID_SELF,
> +		.space = XENMAPSPACE_gmfn_foreign,
> +
> +		.foreign_domid = domid,
> +	};
> +
> +	if (foreign_map_buffer_pfn + nr > ((FOREIGN_MAP_BUFFER +
> +					FOREIGN_MAP_BUFFER_SIZE)>>PAGE_SHIFT)) {
> +		pr_crit("RAM out of foreign map buffers...\n");
> +		return -EBUSY;
> +	}
> +
> +	for (i = 0; i < nr; i++) {
> +		xatp.idx = mfn + i;
> +		xatp.gpfn = foreign_map_buffer_pfn + i;
> +		rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
> +		if (rc != 0) {
> +			pr_crit("foreign map add_to_physmap failed, err=%d\n", rc);
> +			goto out;
> +		}
> +	}
> +
> +	rmd.mfn = foreign_map_buffer_pfn;
> +	rc = apply_to_page_range(vma->vm_mm,
> +				 addr,
> +				 (unsigned long)nr << PAGE_SHIFT,
> +				 remap_area_mfn_pte_fn, &rmd);
> +	if (rc != 0) {
> +		pr_crit("apply_to_page_range failed rc=%d\n", rc);
> +		goto out;
> +	}
> +
> +	foreign_map_buffer_pfn += nr;
> +out:
> +	return rc;
>  }
>  EXPORT_SYMBOL_GPL(xen_remap_domain_mfn_range);
>  
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index 85226cb..3e15c22 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -20,6 +20,8 @@
>  #include <linux/pagemap.h>
>  #include <linux/seq_file.h>
>  #include <linux/miscdevice.h>
> +#include <linux/resource.h>
> +#include <linux/ioport.h>
>  
>  #include <asm/pgalloc.h>
>  #include <asm/pgtable.h>
> @@ -196,9 +198,6 @@ static long privcmd_ioctl_mmap(void __user *udata)
>  	LIST_HEAD(pagelist);
>  	struct mmap_mfn_state state;
>  
> -	if (!xen_initial_domain())
> -		return -EPERM;
> -
>  	if (copy_from_user(&mmapcmd, udata, sizeof(mmapcmd)))
>  		return -EFAULT;
>  
> @@ -286,9 +285,6 @@ static long privcmd_ioctl_mmap_batch(void __user *udata)
>  	LIST_HEAD(pagelist);
>  	struct mmap_batch_state state;
>  
> -	if (!xen_initial_domain())
> -		return -EPERM;
> -
>  	if (copy_from_user(&m, udata, sizeof(m)))
>  		return -EFAULT;
>  
> @@ -365,6 +361,11 @@ static long privcmd_ioctl(struct file *file,
>  	return ret;
>  }
>  
> +static void privcmd_close(struct vm_area_struct *vma)
> +{
> +	/* TODO: unmap VMA */
> +}
> +
>  static int privcmd_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
>  {
>  	printk(KERN_DEBUG "privcmd_fault: vma=%p %lx-%lx, pgoff=%lx, uv=%p\n",
> @@ -375,7 +376,8 @@ static int privcmd_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
>  }
>  
>  static struct vm_operations_struct privcmd_vm_ops = {
> -	.fault = privcmd_fault
> +	.fault = privcmd_fault,
> +	.close = privcmd_close,
>  };
>  
>  static int privcmd_mmap(struct file *file, struct vm_area_struct *vma)
> diff --git a/drivers/xen/xenfs/super.c b/drivers/xen/xenfs/super.c
> index a84b53c..edbe22f 100644
> --- a/drivers/xen/xenfs/super.c
> +++ b/drivers/xen/xenfs/super.c
> @@ -12,6 +12,7 @@
>  #include <linux/module.h>
>  #include <linux/fs.h>
>  #include <linux/magic.h>
> +#include <linux/ioport.h>
>  
>  #include <xen/xen.h>
>  
> @@ -80,6 +81,8 @@ static const struct file_operations capabilities_file_ops = {
>  	.llseek = default_llseek,
>  };
>  
> +extern struct resource foreign_map_resource;
> +
>  static int xenfs_fill_super(struct super_block *sb, void *data, int silent)
>  {
>  	static struct tree_descr xenfs_files[] = {
> @@ -100,6 +103,10 @@ static int xenfs_fill_super(struct super_block *sb, void *data, int silent)
>  				  &xsd_kva_file_ops, NULL, S_IRUSR|S_IWUSR);
>  		xenfs_create_file(sb, sb->s_root, "xsd_port",
>  				  &xsd_port_file_ops, NULL, S_IRUSR|S_IWUSR);
> +		rc = request_resource(&iomem_resource, &foreign_map_resource);
> +		if (rc < 0)
> +			pr_crit("failed to register foreign map resource\n");
> +		rc = 0; /* ignore */
>  	}
>  
>  	return rc;
> diff --git a/include/xen/interface/memory.h b/include/xen/interface/memory.h
> index b66d04c..dd2ffe0 100644
> --- a/include/xen/interface/memory.h
> +++ b/include/xen/interface/memory.h
> @@ -163,12 +163,19 @@ struct xen_add_to_physmap {
>      /* Which domain to change the mapping for. */
>      domid_t domid;
>  
> -    /* Number of pages to go through for gmfn_range */
> -    uint16_t    size;
> +    union {
> +        /* Number of pages to go through for gmfn_range */
> +        uint16_t    size;
> +        /* IFF gmfn_foreign */
> +        domid_t foreign_domid;
> +    };
>  
>      /* Source mapping space. */
> -#define XENMAPSPACE_shared_info 0 /* shared info page */
> -#define XENMAPSPACE_grant_table 1 /* grant table page */
> +#define XENMAPSPACE_shared_info  0 /* shared info page */
> +#define XENMAPSPACE_grant_table  1 /* grant table page */
> +#define XENMAPSPACE_gmfn         2 /* GMFN */
> +#define XENMAPSPACE_gmfn_range   3 /* GMFN range */
> +#define XENMAPSPACE_gmfn_foreign 4 /* GMFN from another guest */
>      unsigned int space;
>  
>      /* Index into source mapping space. */
> -- 
> 1.7.2.5