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xen/arm: introduce XENFEAT_direct_mapped and XENFEAT_not_direct_mapped

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Newer Xen versions expose two Xen feature flags to tell us if the domain
is directly mapped or not. Only when a domain is directly mapped it
makes sense to enable swiotlb-xen on ARM.

Introduce a function on ARM to check the new Xen feature flags and also
to deal with the legacy case. Call the function xen_swiotlb_detect.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20210319200140.12512-1-sstabellini@kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Stefano Stabellini 2021-03-19 13:01:40 -07:00 committed by Juergen Gross
parent a929e12406
commit f5079a9a2a
7 changed files with 38 additions and 2 deletions
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1
arch/arm/include/asm/xen/swiotlb-xen.h Normal file
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@ -0,0 +1 @@
#include <xen/arm/swiotlb-xen.h>

14
arch/arm/xen/mm.c
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@ -135,10 +135,22 @@ 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;
if (!xen_initial_domain())
if (!xen_swiotlb_detect())
return 0;
xen_swiotlb_init(1, false);

1
arch/arm64/include/asm/xen/swiotlb-xen.h Normal file
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@ -0,0 +1 @@
#include <xen/arm/swiotlb-xen.h>

2
arch/arm64/mm/dma-mapping.c
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@ -53,7 +53,7 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
iommu_setup_dma_ops(dev, dma_base, size);
#ifdef CONFIG_XEN
if (xen_initial_domain())
if (xen_swiotlb_detect())
dev->dma_ops = &xen_swiotlb_dma_ops;
#endif
}

7
include/xen/arm/swiotlb-xen.h Normal file
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@ -0,0 +1,7 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_ARM_SWIOTLB_XEN_H
#define _ASM_ARM_SWIOTLB_XEN_H
extern int xen_swiotlb_detect(void);
#endif /* _ASM_ARM_SWIOTLB_XEN_H */

14
include/xen/interface/features.h
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@ -83,6 +83,20 @@
*/
#define XENFEAT_linux_rsdp_unrestricted 15
/*
* A direct-mapped (or 1:1 mapped) domain is a domain for which its
* local pages have gfn == mfn. If a domain is direct-mapped,
* XENFEAT_direct_mapped is set; otherwise XENFEAT_not_direct_mapped
* is set.
*
* If neither flag is set (e.g. older Xen releases) the assumptions are:
* - not auto_translated domains (x86 only) are always direct-mapped
* - on x86, auto_translated domains are not direct-mapped
* - on ARM, Dom0 is direct-mapped, DomUs are not
*/
#define XENFEAT_not_direct_mapped 16
#define XENFEAT_direct_mapped 17
#define XENFEAT_NR_SUBMAPS 1
#endif /* __XEN_PUBLIC_FEATURES_H__ */

1
include/xen/swiotlb-xen.h
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@ -3,6 +3,7 @@
#define __LINUX_SWIOTLB_XEN_H
#include <linux/swiotlb.h>
#include <asm/xen/swiotlb-xen.h>
void xen_dma_sync_for_cpu(struct device *dev, dma_addr_t handle,
size_t size, enum dma_data_direction dir);