[PATCH v2 3/7] PCI: Honor alignment overrides
From: Ilpo Järvinen
Date: Fri Oct 02 2026 - 07:34:48 EST
pci=resource_alignment argument can override the default alignment for
the resource. The remainder code introduced in the commit 9036bd0efcb6
("PCI: Align head space better") can move remainder space (non-aligning
part of the size) before the aligning left edge which results in
violating the requested alignment.
Introduce struct pci_resreq_data to hold device and user-given alignment
to be able to honor it in pci_align_resource(). When user-given alignment
is found, any remainder movement is skipped.
Fixes: 9036bd0efcb6 ("PCI: Align head space better")
Reported-by: Sashiko <sashiko-bot@xxxxxxxxxx>
Link: https://lore.kernel.org/linux-pci/20260923133202.07DF61F000FF@xxxxxxxxxxxxxxx/
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
---
arch/alpha/kernel/pci.c | 3 ++-
arch/arm/kernel/bios32.c | 5 +++--
arch/m68k/kernel/pcibios.c | 4 ++--
arch/mips/pci/pci-generic.c | 5 +++--
arch/mips/pci/pci-legacy.c | 5 +++--
arch/parisc/kernel/pci.c | 5 +++--
arch/powerpc/kernel/pci-common.c | 5 +++--
arch/sh/drivers/pci/pci.c | 5 +++--
arch/x86/pci/i386.c | 5 +++--
arch/xtensa/kernel/pci.c | 5 +++--
drivers/char/agp/intel-gtt.c | 5 ++++-
drivers/gpu/drm/i915/i915_gmch.c | 5 +++--
drivers/pci/pci.c | 5 +++--
drivers/pci/setup-res.c | 19 +++++++++++++------
include/linux/pci.h | 26 ++++++++++++++++++++++++--
15 files changed, 75 insertions(+), 32 deletions(-)
diff --git a/arch/alpha/kernel/pci.c b/arch/alpha/kernel/pci.c
index 11df411b1d18..c5d725a9781f 100644
--- a/arch/alpha/kernel/pci.c
+++ b/arch/alpha/kernel/pci.c
@@ -128,7 +128,8 @@ pcibios_align_resource(void *data, const struct resource *res,
const struct resource *empty_res,
resource_size_t size, resource_size_t align)
{
- struct pci_dev *dev = data;
+ struct pci_resreq_data *rr = data;
+ struct pci_dev *dev = rr->dev;
struct pci_controller *hose = dev->sysdata;
unsigned long alignto;
resource_size_t start = res->start;
diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
index ac0e890510da..3e61826f07fb 100644
--- a/arch/arm/kernel/bios32.c
+++ b/arch/arm/kernel/bios32.c
@@ -564,7 +564,8 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
resource_size_t size,
resource_size_t align)
{
- struct pci_dev *dev = data;
+ struct pci_resreq_data *rr = data;
+ struct pci_dev *dev = rr->dev;
resource_size_t start = res->start;
struct pci_host_bridge *host_bridge;
@@ -578,7 +579,7 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
start, size, align);
if (res->flags & IORESOURCE_MEM)
- return pci_align_resource(dev, res, empty_res, size, align);
+ return pci_align_resource(rr, res, empty_res, size, align);
return start;
}
diff --git a/arch/m68k/kernel/pcibios.c b/arch/m68k/kernel/pcibios.c
index 7a9e60df79c5..3024408412bc 100644
--- a/arch/m68k/kernel/pcibios.c
+++ b/arch/m68k/kernel/pcibios.c
@@ -31,14 +31,14 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
resource_size_t size,
resource_size_t align)
{
- struct pci_dev *dev = data;
+ struct pci_resreq_data *rr = data;
resource_size_t start = res->start;
if ((res->flags & IORESOURCE_IO) && (start & 0x300))
start = (start + 0x3ff) & ~0x3ff;
if (res->flags & IORESOURCE_MEM)
- return pci_align_resource(dev, res, empty_res, size, align);
+ return pci_align_resource(rr, res, empty_res, size, align);
return start;
}
diff --git a/arch/mips/pci/pci-generic.c b/arch/mips/pci/pci-generic.c
index c2e23d0c1d77..7f3ecb91b85b 100644
--- a/arch/mips/pci/pci-generic.c
+++ b/arch/mips/pci/pci-generic.c
@@ -25,7 +25,8 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
const struct resource *empty_res,
resource_size_t size, resource_size_t align)
{
- struct pci_dev *dev = data;
+ struct pci_resreq_data *rr = data;
+ struct pci_dev *dev = rr->dev;
resource_size_t start = res->start;
struct pci_host_bridge *host_bridge;
@@ -39,7 +40,7 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
start, size, align);
if (res->flags & IORESOURCE_MEM)
- return pci_align_resource(dev, res, empty_res, size, align);
+ return pci_align_resource(rr, res, empty_res, size, align);
return start;
}
diff --git a/arch/mips/pci/pci-legacy.c b/arch/mips/pci/pci-legacy.c
index dae6dafdd6e0..82d4b01db64e 100644
--- a/arch/mips/pci/pci-legacy.c
+++ b/arch/mips/pci/pci-legacy.c
@@ -55,7 +55,8 @@ pcibios_align_resource(void *data, const struct resource *res,
const struct resource *empty_res,
resource_size_t size, resource_size_t align)
{
- struct pci_dev *dev = data;
+ struct pci_resreq_data *rr = data;
+ struct pci_dev *dev = rr->dev;
struct pci_controller *hose = dev->sysdata;
resource_size_t start = res->start;
@@ -70,7 +71,7 @@ pcibios_align_resource(void *data, const struct resource *res,
if (start & 0x300)
start = (start + 0x3ff) & ~0x3ff;
} else if (res->flags & IORESOURCE_MEM) {
- start = pci_align_resource(dev, res, empty_res, size, align);
+ start = pci_align_resource(rr, res, empty_res, size, align);
/* Make sure we start at our min on all hoses */
if (start < PCIBIOS_MIN_MEM + hose->mem_resource->start)
diff --git a/arch/parisc/kernel/pci.c b/arch/parisc/kernel/pci.c
index 518f532ccddc..d582be996051 100644
--- a/arch/parisc/kernel/pci.c
+++ b/arch/parisc/kernel/pci.c
@@ -193,7 +193,8 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
resource_size_t size,
resource_size_t alignment)
{
- struct pci_dev *dev = data;
+ struct pci_resreq_data *rr = data;
+ struct pci_dev *dev = rr->dev;
resource_size_t align, start = res->start;
pci_dbg(dev, "%pR: pcibios_align_resource(%lx, 0x%llx, 0x%llx), parent %pR\n",
@@ -205,7 +206,7 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
if (align > alignment)
start = ALIGN(start, align);
else
- start = pci_align_resource(dev, res, empty_res, size, alignment);
+ start = pci_align_resource(rr, res, empty_res, size, alignment);
return start;
}
diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index 4fc52c21fe5d..23594759cfe2 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -1131,7 +1131,8 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
resource_size_t size,
resource_size_t align)
{
- struct pci_dev *dev = data;
+ struct pci_resreq_data *rr = data;
+ struct pci_dev *dev = rr->dev;
resource_size_t start = res->start;
if (res->flags & IORESOURCE_IO) {
@@ -1140,7 +1141,7 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
if (start & 0x300)
start = (start + 0x3ff) & ~0x3ff;
} else if (res->flags & IORESOURCE_MEM) {
- start = pci_align_resource(dev, res, empty_res, size, align);
+ start = pci_align_resource(rr, res, empty_res, size, align);
}
return start;
diff --git a/arch/sh/drivers/pci/pci.c b/arch/sh/drivers/pci/pci.c
index 878a27a1acfb..279f2770ff4b 100644
--- a/arch/sh/drivers/pci/pci.c
+++ b/arch/sh/drivers/pci/pci.c
@@ -172,7 +172,8 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
resource_size_t size,
resource_size_t align)
{
- struct pci_dev *dev = data;
+ struct pci_resreq_data *rr = data;
+ struct pci_dev *dev = rr->dev;
struct pci_channel *hose = dev->sysdata;
resource_size_t start = res->start;
@@ -186,7 +187,7 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
if (start & 0x300)
start = (start + 0x3ff) & ~0x3ff;
} else if (res->flags & IORESOURCE_MEM) {
- start = pci_align_resource(dev, res, empty_res, size, align);
+ start = pci_align_resource(rr, res, empty_res, size, align);
}
return start;
diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
index e2de26b82940..4178ae4380c2 100644
--- a/arch/x86/pci/i386.c
+++ b/arch/x86/pci/i386.c
@@ -156,7 +156,8 @@ pcibios_align_resource(void *data, const struct resource *res,
const struct resource *empty_res,
resource_size_t size, resource_size_t align)
{
- struct pci_dev *dev = data;
+ struct pci_resreq_data *rr = data;
+ struct pci_dev *dev = rr->dev;
resource_size_t start = res->start;
if (res->flags & IORESOURCE_IO) {
@@ -165,7 +166,7 @@ pcibios_align_resource(void *data, const struct resource *res,
if (start & 0x300)
start = (start + 0x3ff) & ~0x3ff;
} else if (res->flags & IORESOURCE_MEM) {
- start = pci_align_resource(dev, res, empty_res, size, align);
+ start = pci_align_resource(rr, res, empty_res, size, align);
/* The low 1MB range is reserved for ISA cards */
if (start < BIOS_END)
diff --git a/arch/xtensa/kernel/pci.c b/arch/xtensa/kernel/pci.c
index 305031551136..4e8ad4a3c9fe 100644
--- a/arch/xtensa/kernel/pci.c
+++ b/arch/xtensa/kernel/pci.c
@@ -42,7 +42,8 @@ pcibios_align_resource(void *data, const struct resource *res,
const struct resource *empty_res,
resource_size_t size, resource_size_t align)
{
- struct pci_dev *dev = data;
+ struct pci_resreq_data *rr = data;
+ struct pci_dev *dev = rr->dev;
resource_size_t start = res->start;
if (res->flags & IORESOURCE_IO) {
@@ -55,7 +56,7 @@ pcibios_align_resource(void *data, const struct resource *res,
if (start & 0x300)
start = (start + 0x3ff) & ~0x3ff;
} else if (res->flags & IORESOURCE_MEM) {
- start = pci_align_resource(dev, res, empty_res, size, align);
+ start = pci_align_resource(rr, res, empty_res, size, align);
}
return start;
diff --git a/drivers/char/agp/intel-gtt.c b/drivers/char/agp/intel-gtt.c
index bcc26785175d..2214347906a6 100644
--- a/drivers/char/agp/intel-gtt.c
+++ b/drivers/char/agp/intel-gtt.c
@@ -1038,10 +1038,13 @@ static struct agp_memory *intel_fake_agp_alloc_by_type(size_t pg_count,
static int intel_alloc_chipset_flush_resource(void)
{
+ struct pci_resreq_data rr;
int ret;
+
+ pci_init_pci_resreq_data(&rr, intel_private.bridge_dev);
ret = pci_bus_alloc_resource(intel_private.bridge_dev->bus, &intel_private.ifp_resource, PAGE_SIZE,
PAGE_SIZE, PCIBIOS_MIN_MEM, 0,
- pcibios_align_resource, intel_private.bridge_dev);
+ pcibios_align_resource, &rr);
return ret;
}
diff --git a/drivers/gpu/drm/i915/i915_gmch.c b/drivers/gpu/drm/i915/i915_gmch.c
index b0ef6ef577a3..d35097bebc0f 100644
--- a/drivers/gpu/drm/i915/i915_gmch.c
+++ b/drivers/gpu/drm/i915/i915_gmch.c
@@ -38,6 +38,7 @@ static int mchbar_reg(struct drm_i915_private *i915)
static int
intel_alloc_mchbar_resource(struct drm_i915_private *i915)
{
+ struct pci_resreq_data rr;
u32 temp_lo, temp_hi = 0;
u64 mchbar_addr;
int ret;
@@ -55,12 +56,12 @@ intel_alloc_mchbar_resource(struct drm_i915_private *i915)
/* Get some space for it */
i915->gmch.mch_res.name = "i915 MCHBAR";
i915->gmch.mch_res.flags = IORESOURCE_MEM;
+ pci_init_pci_resreq_data(&rr, i915->gmch.pdev);
ret = pci_bus_alloc_resource(i915->gmch.pdev->bus,
&i915->gmch.mch_res,
MCHBAR_SIZE, MCHBAR_SIZE,
PCIBIOS_MIN_MEM,
- 0, pcibios_align_resource,
- i915->gmch.pdev);
+ 0, pcibios_align_resource, &rr);
if (ret) {
drm_dbg(&i915->drm, "failed bus alloc: %d\n", ret);
i915->gmch.mch_res.start = 0;
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b2879a6be5f8..1b7a4469c6ca 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -6444,8 +6444,8 @@ static DEFINE_SPINLOCK(resource_alignment_lock);
* RETURNS: Resource alignment if it is specified.
* Zero if it is not specified.
*/
-static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev,
- bool *resize)
+resource_size_t pci_specified_resource_alignment(struct pci_dev *dev,
+ bool *resize)
{
int align_order, count;
resource_size_t align = pcibios_default_alignment();
@@ -6497,6 +6497,7 @@ static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev,
spin_unlock(&resource_alignment_lock);
return align;
}
+EXPORT_SYMBOL_GPL(pci_specified_resource_alignment);
static void pci_request_resource_alignment(struct pci_dev *dev, int bar,
resource_size_t align, bool resize)
diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index 376f09630a4a..441a62807719 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -265,17 +265,21 @@ resource_size_t pci_resource_alignment(const struct pci_dev *dev,
* before res->start if there's enough free space there. This enables
* tighter packing for resources.
*/
-resource_size_t pci_align_resource(struct pci_dev *dev,
+resource_size_t pci_align_resource(struct pci_resreq_data *rr,
const struct resource *res,
const struct resource *empty_res,
resource_size_t size,
resource_size_t align)
{
+ struct pci_dev *dev = rr->dev;
resource_size_t remainder, start_addr;
if (!(res->flags & IORESOURCE_MEM))
return res->start;
+ if (rr->user_align)
+ return res->start;
+
if (IS_ALIGNED(size, align))
return res->start;
@@ -306,18 +310,21 @@ resource_size_t __weak pcibios_align_resource(void *data,
resource_size_t size,
resource_size_t align)
{
- struct pci_dev *dev = data;
+ struct pci_resreq_data *rr = data;
- return pci_align_resource(dev, res, empty_res, size, align);
+ return pci_align_resource(rr, res, empty_res, size, align);
}
static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev,
int resno, resource_size_t size, resource_size_t align)
{
struct resource *res = pci_resource_n(dev, resno);
+ struct pci_resreq_data rr;
resource_size_t min;
int ret;
+ pci_init_pci_resreq_data(&rr, dev);
+
min = (res->flags & IORESOURCE_IO) ? PCIBIOS_MIN_IO : PCIBIOS_MIN_MEM;
/*
@@ -329,7 +336,7 @@ static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev,
*/
ret = pci_bus_alloc_resource(bus, res, size, align, min,
IORESOURCE_PREFETCH | IORESOURCE_MEM_64,
- pcibios_align_resource, dev);
+ pcibios_align_resource, &rr);
if (ret == 0)
return 0;
@@ -341,7 +348,7 @@ static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev,
(IORESOURCE_PREFETCH | IORESOURCE_MEM_64)) {
ret = pci_bus_alloc_resource(bus, res, size, align, min,
IORESOURCE_PREFETCH,
- pcibios_align_resource, dev);
+ pcibios_align_resource, &rr);
if (ret == 0)
return 0;
}
@@ -354,7 +361,7 @@ static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev,
*/
if (res->flags & (IORESOURCE_PREFETCH | IORESOURCE_MEM_64))
ret = pci_bus_alloc_resource(bus, res, size, align, min, 0,
- pcibios_align_resource, dev);
+ pcibios_align_resource, &rr);
return ret;
}
diff --git a/include/linux/pci.h b/include/linux/pci.h
index d31a8d107b1e..fe0233f0d9e6 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1217,12 +1217,34 @@ int __must_check pcibios_enable_device(struct pci_dev *, int mask);
/* Architecture-specific versions may override this (weak) */
char *pcibios_setup(char *str);
-/* Used only when drivers/pci/setup.c is used */
+/* Resource assignment request handling */
+/**
+ * struct pci_resreq_data - Data passed to pcibios_align_resource()
+ * @dev: PCI device
+ * @user_align: User provided alignment override (pci=resource_alignment param)
+ */
+struct pci_resreq_data {
+ struct pci_dev *dev;
+ resource_size_t user_align;
+};
+
+resource_size_t pci_specified_resource_alignment(struct pci_dev *dev,
+ bool *resize);
+static inline void pci_init_pci_resreq_data(struct pci_resreq_data *rr,
+ struct pci_dev *dev)
+{
+ bool user_aligned;
+
+ memset(rr, 0, sizeof(*rr));
+ rr->dev = dev;
+ rr->user_align = pci_specified_resource_alignment(dev, &user_aligned);
+}
+
resource_size_t pcibios_align_resource(void *data, const struct resource *res,
const struct resource *empty_res,
resource_size_t size,
resource_size_t align);
-resource_size_t pci_align_resource(struct pci_dev *dev,
+resource_size_t pci_align_resource(struct pci_resreq_data *rr,
const struct resource *res,
const struct resource *empty_res,
resource_size_t size,
--
2.47.3