[PATCH 13/15] swiotlb: merge swiotlb-xen initialization into swiotlb

Christoph Hellwig
2022-03-14T07:32:51Z

Reuse the generic swiotlb initialization for xen-swiotlb. For ARM/ARM64
this works trivially, while for x86 xen_swiotlb_fixup needs to be passed
as the remap argument to swiotlb_init_remap/swiotlb_init_late.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
arch/arm/xen/mm.c | 21 +++---
arch/x86/include/asm/xen/page.h | 5 --
arch/x86/kernel/pci-dma.c | 19 +++--
drivers/xen/swiotlb-xen.c | 128 +-------------------------------
include/xen/arm/page.h | 1 -
include/xen/swiotlb-xen.h | 8 +-
6 files changed, 27 insertions(+), 155 deletions(-)

diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
index 28c2070602535..ff05a7899cb86 100644
--- a/arch/arm/xen/mm.c
+++ b/arch/arm/xen/mm.c
@@ -23,22 +23,20 @@
#include <asm/xen/hypercall.h>
#include <asm/xen/interface.h>

-unsigned long xen_get_swiotlb_free_pages(unsigned int order)
+static gfp_t xen_swiotlb_gfp(void)
{
phys_addr_t base;
- gfp_t flags = __GFP_NOWARN|__GFP_KSWAPD_RECLAIM;
u64 i;

for_each_mem_range(i, &base, NULL) {
if (base < (phys_addr_t)0xffffffff) {
if (IS_ENABLED(CONFIG_ZONE_DMA32))
- flags |= __GFP_DMA32;
- else
- flags |= __GFP_DMA;
- break;
+ return __GFP_DMA32;
+ return __GFP_DMA;
}
}
- return __get_free_pages(flags, order);
+
+ return GFP_KERNEL;
}

static bool hypercall_cflush = false;
@@ -140,10 +138,13 @@ static int __init xen_mm_init(void)
if (!xen_swiotlb_detect())
return 0;

- rc = xen_swiotlb_init();
/* we can work with the default swiotlb */
- if (rc < 0 && rc != -EEXIST)
- return rc;
+ if (!io_tlb_default_mem.nslabs) {
+ rc = swiotlb_init_late(swiotlb_size_or_default(),
+ xen_swiotlb_gfp(), NULL);
+ if (rc < 0)
+ return rc;
+ }

cflush.op = 0;
cflush.a.dev_bus_addr = 0;
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index e989bc2269f54..1fc67df500145 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -357,9 +357,4 @@ static inline bool xen_arch_need_swiotlb(struct device *dev,
return false;
}

-static inline unsigned long xen_get_swiotlb_free_pages(unsigned int order)
-{
- return __get_free_pages(__GFP_NOWARN, order);
-}
-
#endif /* _ASM_X86_XEN_PAGE_H */
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index a705a199bf8a3..dbb7b83fc3e48 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -72,15 +72,12 @@ static inline void __init pci_swiotlb_detect(void)
#endif /* CONFIG_SWIOTLB */

#ifdef CONFIG_SWIOTLB_XEN
-static bool xen_swiotlb;
-
static void __init pci_xen_swiotlb_init(void)
{
if (!xen_initial_domain() && !x86_swiotlb_enable)
return;
x86_swiotlb_enable = true;
- xen_swiotlb = true;
- xen_swiotlb_init_early();
+ swiotlb_init_remap(true, x86_swiotlb_flags, xen_swiotlb_fixup);
dma_ops = &xen_swiotlb_dma_ops;
if (IS_ENABLED(CONFIG_PCI))
pci_request_acs();
@@ -88,14 +85,16 @@ static void __init pci_xen_swiotlb_init(void)

int pci_xen_swiotlb_init_late(void)
{
- int rc;
-
- if (xen_swiotlb)
+ if (dma_ops == &xen_swiotlb_dma_ops)
return 0;

- rc = xen_swiotlb_init();
- if (rc)
- return rc;
+ /* we can work with the default swiotlb */
+ if (!io_tlb_default_mem.nslabs) {
+ int rc = swiotlb_init_late(swiotlb_size_or_default(),
+ GFP_KERNEL, xen_swiotlb_fixup);
+ if (rc < 0)
+ return rc;
+ }

/* XXX: this switches the dma ops under live devices! */
dma_ops = &xen_swiotlb_dma_ops;
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index c2da3eb4826e8..df8085b50df10 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -104,7 +104,7 @@ static int is_xen_swiotlb_buffer(struct device *dev, dma_addr_t dma_addr)
return 0;
}

-static int xen_swiotlb_fixup(void *buf, unsigned long nslabs)
+int xen_swiotlb_fixup(void *buf, unsigned long nslabs)
{
int rc;
unsigned int order = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT);
@@ -130,132 +130,6 @@ static int xen_swiotlb_fixup(void *buf, unsigned long nslabs)
return 0;
}

-enum xen_swiotlb_err {
- XEN_SWIOTLB_UNKNOWN = 0,
- XEN_SWIOTLB_ENOMEM,
- XEN_SWIOTLB_EFIXUP
-};
-
-static const char *xen_swiotlb_error(enum xen_swiotlb_err err)
-{
- switch (err) {
- case XEN_SWIOTLB_ENOMEM:
- return "Cannot allocate Xen-SWIOTLB buffer\n";
- case XEN_SWIOTLB_EFIXUP:
- return "Failed to get contiguous memory for DMA from Xen!\n"\
- "You either: don't have the permissions, do not have"\
- " enough free memory under 4GB, or the hypervisor memory"\
- " is too fragmented!";
- default:
- break;
- }
- return "";
-}
-
-int xen_swiotlb_init(void)
-{
- enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN;
- unsigned long bytes = swiotlb_size_or_default();
- unsigned long nslabs = bytes >> IO_TLB_SHIFT;
- unsigned int order, repeat = 3;
- int rc = -ENOMEM;
- char *start;
-
- if (io_tlb_default_mem.nslabs) {
- pr_warn("swiotlb buffer already initialized\n");
- return -EEXIST;
- }
-
-retry:
- m_ret = XEN_SWIOTLB_ENOMEM;
- order = get_order(bytes);
-
- /*
- * Get IO TLB memory from any location.
- */
-#define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
-#define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
- while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
- start = (void *)xen_get_swiotlb_free_pages(order);
- if (start)
- break;
- order--;
- }
- if (!start)
- goto exit;
- if (order != get_order(bytes)) {
- pr_warn("Warning: only able to allocate %ld MB for software IO TLB\n",
- (PAGE_SIZE << order) >> 20);
- nslabs = SLABS_PER_PAGE << order;
- bytes = nslabs << IO_TLB_SHIFT;
- }
-
- /*
- * And replace that memory with pages under 4GB.
- */
- rc = xen_swiotlb_fixup(start, nslabs);
- if (rc) {
- free_pages((unsigned long)start, order);
- m_ret = XEN_SWIOTLB_EFIXUP;
- goto error;
- }
- rc = swiotlb_late_init_with_tbl(start, nslabs);
- if (rc)
- return rc;
- return 0;
-error:
- if (nslabs > 1024 && repeat--) {
- /* Min is 2MB */
- nslabs = max(1024UL, ALIGN(nslabs >> 1, IO_TLB_SEGSIZE));
- bytes = nslabs << IO_TLB_SHIFT;
- pr_info("Lowering to %luMB\n", bytes >> 20);
- goto retry;
- }
-exit:
- pr_err("%s (rc:%d)\n", xen_swiotlb_error(m_ret), rc);
- return rc;
-}
-
-#ifdef CONFIG_X86
-void __init xen_swiotlb_init_early(void)
-{
- unsigned long bytes = swiotlb_size_or_default();
- unsigned long nslabs = bytes >> IO_TLB_SHIFT;
- unsigned int repeat = 3;
- char *start;
- int rc;
-
-retry:
- /*
- * Get IO TLB memory from any location.
- */
- start = memblock_alloc(PAGE_ALIGN(bytes),
- IO_TLB_SEGSIZE << IO_TLB_SHIFT);
- if (!start)
- panic("%s: Failed to allocate %lu bytes\n",
- __func__, PAGE_ALIGN(bytes));
-
- /*
- * And replace that memory with pages under 4GB.
- */
- rc = xen_swiotlb_fixup(start, nslabs);
- if (rc) {
- memblock_free(start, PAGE_ALIGN(bytes));
- if (nslabs > 1024 && repeat--) {
- /* Min is 2MB */
- nslabs = max(1024UL, ALIGN(nslabs >> 1, IO_TLB_SEGSIZE));
- bytes = nslabs << IO_TLB_SHIFT;
- pr_info("Lowering to %luMB\n", bytes >> 20);
- goto retry;
- }
- panic("%s (rc:%d)", xen_swiotlb_error(XEN_SWIOTLB_EFIXUP), rc);
- }
-
- if (swiotlb_init_with_tbl(start, nslabs, SWIOTLB_VERBOSE))
- panic("Cannot allocate SWIOTLB buffer");
-}
-#endif /* CONFIG_X86 */
-
static void *
xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
dma_addr_t *dma_handle, gfp_t flags,
diff --git a/include/xen/arm/page.h b/include/xen/arm/page.h
index ac1b654705631..7e199c6656b90 100644
--- a/include/xen/arm/page.h
+++ b/include/xen/arm/page.h
@@ -115,6 +115,5 @@ static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
bool xen_arch_need_swiotlb(struct device *dev,
phys_addr_t phys,
dma_addr_t dev_addr);
-unsigned long xen_get_swiotlb_free_pages(unsigned int order);

#endif /* _ASM_ARM_XEN_PAGE_H */
diff --git a/include/xen/swiotlb-xen.h b/include/xen/swiotlb-xen.h
index b3e647f86e3e2..590ceb923f0c8 100644
--- a/include/xen/swiotlb-xen.h
+++ b/include/xen/swiotlb-xen.h
@@ -10,8 +10,12 @@ void xen_dma_sync_for_cpu(struct device *dev, dma_addr_t handle,
void xen_dma_sync_for_device(struct device *dev, dma_addr_t handle,
size_t size, enum dma_data_direction dir);

-int xen_swiotlb_init(void);
-void __init xen_swiotlb_init_early(void);
+#ifdef CONFIG_SWIOTLB_XEN
+int xen_swiotlb_fixup(void *buf, unsigned long nslabs);
+#else
+#define xen_swiotlb_fixup NULL
+#endif
+
extern const struct dma_map_ops xen_swiotlb_dma_ops;

#endif /* __LINUX_SWIOTLB_XEN_H */
--
2.30.2