linux-kernel - Re: [PATCH 10/10] xen/swiotlb: Depending on after

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Date:	Fri, 14 Sep 2012 17:10:48 +0100
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
	Stefano Stabellini <Stefano.Stabellini@...citrix.com>
Subject: Re: [PATCH 10/10] xen/swiotlb: Depending on after_bootmem is not
 correct.

On Mon, 10 Sep 2012, Konrad Rzeszutek Wilk wrote:
> When PCI IOMMUs are initialized it is after after_bootmem but
> before a lot of "other" subsystems are initialized. As such
> the check for after_bootmem is incorrect and we should
> just use a parameter to define whether we are early or late.
> 
> This solves this bootup problem:
> 
> __ex_table already sorted, skipping sortM
> Initializing CPU#0
> Warning: only able to allocate 1 MB for software IO TLB
> Xen-SWIOTLB: Lowering to 2MB
> Warning: only able to allocate 1 MB for software IO TLB
> Xen-SWIOTLB: Lowering to 2MB
> Warning: only able to allocate 1 MB for software IO TLB
> Xen-SWIOTLB: Lowering to 2MB
> Warning: only able to allocate 1 MB for software IO TLB
> Cannot allocate Xen-SWIOTLB buffer (rc:-12)
> 
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> ---
>  arch/x86/xen/pci-swiotlb-xen.c |    4 ++--
>  drivers/xen/swiotlb-xen.c      |   11 ++++++-----
>  include/xen/swiotlb-xen.h      |    2 +-
>  3 files changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c
> index fc0c78f..1608244 100644
> --- a/arch/x86/xen/pci-swiotlb-xen.c
> +++ b/arch/x86/xen/pci-swiotlb-xen.c
> @@ -69,7 +69,7 @@ int __init pci_xen_swiotlb_detect(void)
>  void __init pci_xen_swiotlb_init(void)
>  {
>  	if (xen_swiotlb) {
> -		xen_swiotlb_init(1);
> +		xen_swiotlb_init(1, true /* early */);
>  		dma_ops = &xen_swiotlb_dma_ops;
>  
>  		/* Make sure ACS will be enabled */
> @@ -84,7 +84,7 @@ int pci_xen_swiotlb_init_late(void)
>  	if (xen_swiotlb)
>  		return 0;
>  
> -	rc = xen_swiotlb_init(1);
> +	rc = xen_swiotlb_init(1, false /* late */);
>  	if (rc)
>  		return rc;
>  
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index 6f81994..7443e19 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -176,7 +176,7 @@ static const char *xen_swiotlb_error(enum xen_swiotlb_err err)
>  	}
>  	return "";
>  }
> -int __ref xen_swiotlb_init(int verbose)
> +int __ref xen_swiotlb_init(int verbose, bool early)
>  {
>  	unsigned long bytes, order;
>  	int rc = -ENOMEM;
> @@ -190,7 +190,7 @@ retry:
>  	/*
>  	 * Get IO TLB memory from any location.
>  	 */
> -	if (!after_bootmem)
> +	if (early)
>  		xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes));
>  	else {
>  #define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
> @@ -220,7 +220,7 @@ retry:
>  			       bytes,
>  			       xen_io_tlb_nslabs);
>  	if (rc) {
> -		if (!after_bootmem)
> +		if (early)
>  			free_bootmem(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes));
>  		else {
>  			free_pages((unsigned long)xen_io_tlb_start, order);
> @@ -230,7 +230,8 @@ retry:
>  		goto error;
>  	}
>  	start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
> -	if (!after_bootmem)
> +	rc = 0;
     ^
why does this change belong to this patch?


> +	if (early)
>  		swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, verbose);
>  	else
>  		rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);
> @@ -244,7 +245,7 @@ error:
>  		goto retry;
>  	}
>  	pr_err("%s (rc:%d)", xen_swiotlb_error(m_ret), rc);
> -	if (!after_bootmem)
> +	if (early)
>  		panic("%s (rc:%d)", xen_swiotlb_error(m_ret), rc);
>  	else
>  		free_pages((unsigned long)xen_io_tlb_start, order);
> diff --git a/include/xen/swiotlb-xen.h b/include/xen/swiotlb-xen.h
> index a0db2b7..de8bcc6 100644
> --- a/include/xen/swiotlb-xen.h
> +++ b/include/xen/swiotlb-xen.h
> @@ -3,7 +3,7 @@
>  
>  #include <linux/swiotlb.h>
>  
> -extern int xen_swiotlb_init(int verbose);
> +extern int xen_swiotlb_init(int verbose, bool early);
>  
>  extern void
>  *xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
> -- 
> 1.7.7.6
> 
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