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Message-ID: <20250211120432.29493-3-jgross@suse.com>
Date: Tue, 11 Feb 2025 13:04:32 +0100
From: Juergen Gross <jgross@...e.com>
To: linux-kernel@...r.kernel.org,
x86@...nel.org,
iommu@...ts.linux.dev
Cc: Juergen Gross <jgross@...e.com>,
Stefano Stabellini <sstabellini@...nel.org>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"H. Peter Anvin" <hpa@...or.com>,
Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
xen-devel@...ts.xenproject.org
Subject: [PATCH 2/2] xen/swiotlb: don't destroy contiguous region in all cases
In case xen_swiotlb_alloc_coherent() needed to create a contiguous
region only for other reason than the memory not being compliant with
the device's DMA mask, there is no reason why this contiguous region
should be destroyed by xen_swiotlb_free_coherent() later. Destroying
this region should be done only, if the memory of the region was
allocated with more stringent placement requirements than the memory
it did replace.
Signed-off-by: Juergen Gross <jgross@...e.com>
---
arch/x86/include/asm/xen/swiotlb-xen.h | 5 +++--
arch/x86/xen/mmu_pv.c | 18 ++++++++++++------
drivers/xen/swiotlb-xen.c | 11 +++++++----
3 files changed, 22 insertions(+), 12 deletions(-)
diff --git a/arch/x86/include/asm/xen/swiotlb-xen.h b/arch/x86/include/asm/xen/swiotlb-xen.h
index abde0f44df57..a353f20c7e79 100644
--- a/arch/x86/include/asm/xen/swiotlb-xen.h
+++ b/arch/x86/include/asm/xen/swiotlb-xen.h
@@ -4,8 +4,9 @@
int xen_swiotlb_fixup(void *buf, unsigned long nslabs);
int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
- unsigned int address_bits,
- dma_addr_t *dma_handle);
+ unsigned int address_bits,
+ dma_addr_t *dma_handle,
+ unsigned int *address_bits_in);
void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order);
#endif /* _ASM_X86_SWIOTLB_XEN_H */
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index 2c70cd35e72c..fb586238f7c4 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -2208,19 +2208,22 @@ void __init xen_init_mmu_ops(void)
static unsigned long discontig_frames[1<<MAX_CONTIG_ORDER];
#define VOID_PTE (mfn_pte(0, __pgprot(0)))
-static void xen_zap_pfn_range(unsigned long vaddr, unsigned int order,
- unsigned long *in_frames,
- unsigned long *out_frames)
+static int xen_zap_pfn_range(unsigned long vaddr, unsigned int order,
+ unsigned long *in_frames,
+ unsigned long *out_frames)
{
int i;
+ u64 address_bits = 0;
struct multicall_space mcs;
xen_mc_batch();
for (i = 0; i < (1UL<<order); i++, vaddr += PAGE_SIZE) {
mcs = __xen_mc_entry(0);
- if (in_frames)
+ if (in_frames) {
in_frames[i] = virt_to_mfn((void *)vaddr);
+ address_bits |= in_frames[i] << PAGE_SHIFT;
+ }
MULTI_update_va_mapping(mcs.mc, vaddr, VOID_PTE, 0);
__set_phys_to_machine(virt_to_pfn((void *)vaddr), INVALID_P2M_ENTRY);
@@ -2229,6 +2232,8 @@ static void xen_zap_pfn_range(unsigned long vaddr, unsigned int order,
out_frames[i] = virt_to_pfn((void *)vaddr);
}
xen_mc_issue(0);
+
+ return fls64(address_bits);
}
/*
@@ -2321,7 +2326,8 @@ static int xen_exchange_memory(unsigned long extents_in, unsigned int order_in,
int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
unsigned int address_bits,
- dma_addr_t *dma_handle)
+ dma_addr_t *dma_handle,
+ unsigned int *address_bits_in)
{
unsigned long *in_frames = discontig_frames, out_frame;
unsigned long flags;
@@ -2336,7 +2342,7 @@ int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
spin_lock_irqsave(&xen_reservation_lock, flags);
/* 1. Zap current PTEs, remembering MFNs. */
- xen_zap_pfn_range(vstart, order, in_frames, NULL);
+ *address_bits_in = xen_zap_pfn_range(vstart, order, in_frames, NULL);
/* 2. Get a new contiguous memory extent. */
out_frame = virt_to_pfn((void *)vstart);
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 26c62e0d34e9..3f3724f53914 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -118,6 +118,7 @@ int xen_swiotlb_fixup(void *buf, unsigned long nslabs)
int rc;
unsigned int order = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT);
unsigned int i, dma_bits = order + PAGE_SHIFT;
+ unsigned int dummy;
dma_addr_t dma_handle;
phys_addr_t p = virt_to_phys(buf);
@@ -129,7 +130,7 @@ int xen_swiotlb_fixup(void *buf, unsigned long nslabs)
do {
rc = xen_create_contiguous_region(
p + (i << IO_TLB_SHIFT), order,
- dma_bits, &dma_handle);
+ dma_bits, &dma_handle, &dummy);
} while (rc && dma_bits++ < MAX_DMA_BITS);
if (rc)
return rc;
@@ -144,6 +145,7 @@ xen_swiotlb_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flags, unsigned long attrs)
{
u64 dma_mask = dev->coherent_dma_mask;
+ unsigned int address_bits = fls64(dma_mask), address_bits_in;
int order = get_order(size);
phys_addr_t phys;
void *ret;
@@ -160,10 +162,11 @@ xen_swiotlb_alloc_coherent(struct device *dev, size_t size,
if (*dma_handle + size - 1 > dma_mask ||
range_straddles_page_boundary(phys, size) ||
range_requires_alignment(phys, size)) {
- if (xen_create_contiguous_region(phys, order, fls64(dma_mask),
- dma_handle) != 0)
+ if (xen_create_contiguous_region(phys, order, address_bits,
+ dma_handle, &address_bits_in))
goto out_free_pages;
- SetPageXenRemapped(virt_to_page(ret));
+ if (address_bits_in > address_bits)
+ SetPageXenRemapped(virt_to_page(ret));
}
memset(ret, 0, size);
--
2.43.0
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