swiotlb-xen: this is PV-only on x86

The code is unreachable for HVM or PVH, and it also makes little sense
in auto-translated environments. On Arm, with
xen_{create,destroy}_contiguous_region() both being stubs, I have a hard
time seeing what good the Xen specific variant does - the generic one
ought to be fine for all purposes there. Still Arm code explicitly
references symbols here, so the code will continue to be included there.

Instead of making PCI_XEN's "select" conditional, simply drop it -
SWIOTLB_XEN will be available unconditionally in the PV case anyway, and
is - as explained above - dead code in non-PV environments.

This in turn allows dropping the stubs for
xen_{create,destroy}_contiguous_region(), the former of which was broken
anyway - it failed to set the DMA handle output.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Link: https://lore.kernel.org/r/5947b8ae-fdc7-225c-4838-84712265fc1e@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 88fb922c23a0ae5df9958314ef952f47c9022841..a71ced4c711fb2610e16b324834728b74cbdba32 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2605,7 +2605,6 @@ config PCI_OLPC
 config PCI_XEN
        def_bool y
        depends on PCI && XEN
-       select SWIOTLB_XEN
 
 config MMCONF_FAM10H
        def_bool y

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index a37eb52fb4010750112d38e5e200c291b288fed6..22f5aff0c1367127dfc73a5a81f1c19f8b7b2ecd 100644 (file)
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -177,6 +177,7 @@ config XEN_GRANT_DMA_ALLOC
 
 config SWIOTLB_XEN
        def_bool y
+       depends on XEN_PV || ARM || ARM64
        select DMA_OPS
        select SWIOTLB
 

diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
index 39a5580f8feb08e6c39b591ae1dd524fa382ecdc..db28e79b77ee7aa4293d9f17ffc02839404a7a3e 100644 (file)
--- a/include/xen/xen-ops.h
+++ b/include/xen/xen-ops.h
@@ -46,19 +46,7 @@ extern unsigned long *xen_contiguous_bitmap;
 int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
                                unsigned int address_bits,
                                dma_addr_t *dma_handle);
-
 void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order);
-#else
-static inline int xen_create_contiguous_region(phys_addr_t pstart,
-                                              unsigned int order,
-                                              unsigned int address_bits,
-                                              dma_addr_t *dma_handle)
-{
-       return 0;
-}
-
-static inline void xen_destroy_contiguous_region(phys_addr_t pstart,
-                                                unsigned int order) { }
 #endif
 
 #if defined(CONFIG_XEN_PV)