2021-05-11 17:43:53

by Stefano Stabellini

Subject: [PATCH 1/2] xen/arm64: do not set SWIOTLB_NO_FORCE when swiotlb is required

From: Stefano Stabellini <[email protected]>

Although SWIOTLB_NO_FORCE is meant to allow later calls to swiotlb_init,
today dma_direct_map_page returns error if SWIOTLB_NO_FORCE.

For now, without a larger overhaul of SWIOTLB_NO_FORCE, the best we can
do is to avoid setting SWIOTLB_NO_FORCE in mem_init when we know that it
is going to be required later (e.g. Xen requires it).

To make xen_swiotlb_detect available to !CONFIG_XEN builds, move it to a
static inline function.

CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: [email protected]
Fixes: 2726bf3ff252 ("swiotlb: Make SWIOTLB_NO_FORCE perform no allocation")
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Stefano Stabellini <[email protected]>
---
arch/arm/xen/mm.c | 12 ------------
arch/arm64/mm/init.c | 3 ++-
include/xen/arm/swiotlb-xen.h | 15 ++++++++++++++-
3 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
index f8f07469d259..223b1151fd7d 100644
--- a/arch/arm/xen/mm.c
+++ b/arch/arm/xen/mm.c
@@ -135,18 +135,6 @@ void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
return;
}

-int xen_swiotlb_detect(void)
-{
- if (!xen_domain())
- return 0;
- if (xen_feature(XENFEAT_direct_mapped))
- return 1;
- /* legacy case */
- if (!xen_feature(XENFEAT_not_direct_mapped) && xen_initial_domain())
- return 1;
- return 0;
-}
-
static int __init xen_mm_init(void)
{
struct gnttab_cache_flush cflush;
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 16a2b2b1c54d..e55409caaee3 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -43,6 +43,7 @@
#include <linux/sizes.h>
#include <asm/tlb.h>
#include <asm/alternative.h>
+#include <asm/xen/swiotlb-xen.h>

/*
* We need to be able to catch inadvertent references to memstart_addr
@@ -482,7 +483,7 @@ void __init mem_init(void)
if (swiotlb_force == SWIOTLB_FORCE ||
max_pfn > PFN_DOWN(arm64_dma_phys_limit))
swiotlb_init(1);
- else
+ else if (!xen_swiotlb_detect())
swiotlb_force = SWIOTLB_NO_FORCE;

set_max_mapnr(max_pfn - PHYS_PFN_OFFSET);
diff --git a/include/xen/arm/swiotlb-xen.h b/include/xen/arm/swiotlb-xen.h
index 2994fe6031a0..33336ab58afc 100644
--- a/include/xen/arm/swiotlb-xen.h
+++ b/include/xen/arm/swiotlb-xen.h
@@ -2,6 +2,19 @@
#ifndef _ASM_ARM_SWIOTLB_XEN_H
#define _ASM_ARM_SWIOTLB_XEN_H

-extern int xen_swiotlb_detect(void);
+#include <xen/features.h>
+#include <xen/xen.h>
+
+static inline int xen_swiotlb_detect(void)
+{
+ if (!xen_domain())
+ return 0;
+ if (xen_feature(XENFEAT_direct_mapped))
+ return 1;
+ /* legacy case */
+ if (!xen_feature(XENFEAT_not_direct_mapped) && xen_initial_domain())
+ return 1;
+ return 0;
+}

#endif /* _ASM_ARM_SWIOTLB_XEN_H */
--
2.17.1

2021-05-12 07:29:21

by Christoph Hellwig

Subject: Re: [PATCH 1/2] xen/arm64: do not set SWIOTLB_NO_FORCE when swiotlb is required

> -int xen_swiotlb_detect(void)
> -{
> - if (!xen_domain())
> - return 0;
> - if (xen_feature(XENFEAT_direct_mapped))
> - return 1;
> - /* legacy case */
> - if (!xen_feature(XENFEAT_not_direct_mapped) && xen_initial_domain())
> - return 1;
> - return 0;
> -}

I think this move should be a separate prep patch.

2021-05-12 20:39:59

by Stefano Stabellini

Subject: Re: [PATCH 1/2] xen/arm64: do not set SWIOTLB_NO_FORCE when swiotlb is required

On Wed, 12 May 2021, Christoph Hellwig wrote:
> > -int xen_swiotlb_detect(void)
> > -{
> > - if (!xen_domain())
> > - return 0;
> > - if (xen_feature(XENFEAT_direct_mapped))
> > - return 1;
> > - /* legacy case */
> > - if (!xen_feature(XENFEAT_not_direct_mapped) && xen_initial_domain())
> > - return 1;
> > - return 0;
> > -}
>
> I think this move should be a separate prep patch.

Sure, I can do that