Re: [PATCH 24/24] [HACK] xen/arm: implement xen_remap_domain_mfn_range

[Konrad Rzeszutek Wilk <konrad.wilk-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

On Thu, Jul 26, 2012 at 04:34:06PM +0100, Stefano Stabellini wrote:
> From: Ian Campbell <Ian.Campbell-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org>
> 
> Do not apply!

Mukesh, I believe this is similar to what you had in mind.

> 
> 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.. We should get this done irrespective of this ARM patchset as
it will certainly benefit the HVM domains.

So  what is with the 0x9000 values?

> 
> Signed-off-by: Ian Campbell <Ian.Campbell-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Stefano Stabellini <stefano.stabellini-mvvWK6WmYclDPfheJLI6IQ@public.gmane.org>
> ---
>  arch/arm/xen/enlighten.c       |   79 +++++++++++++++++++++++++++++++++++++++-
>  drivers/xen/privcmd.c          |   16 +++++----
>  drivers/xen/xenfs/super.c      |    7 ++++
>  include/xen/interface/memory.h |   10 ++++--
>  4 files changed, 101 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
> index 1476b0b..7092015 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 d8e33a9..ec68945 100644
> --- a/include/xen/interface/memory.h
> +++ b/include/xen/interface/memory.h
> @@ -167,9 +167,13 @@ struct xen_add_to_physmap {
>      uint16_t    size;
>  
>      /* Source mapping space. */
> -#define XENMAPSPACE_shared_info 0 /* shared info page */
> -#define XENMAPSPACE_grant_table 1 /* grant table page */
> -    unsigned int space;
> +#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 */
> +    uint16_t space;
> +    domid_t foreign_domid; /* IFF gmfn_foreign */
>  
>      /* Index into source mapping space. */
>      unsigned long idx;
> -- 
> 1.7.2.5