[PATCH v2 02/11] PCI/IOV: Adjust ->barsz[] when changing BAR size

Ilpo Järvinen
2025-11-13T16:27:09Z

pci_rebar_set_size() adjusts BAR size for both normal and IOV BARs. The
struct pci_srvio keeps a cached copy of BAR size in unit of resource_size_t
in ->barsz[] which is not adjusted by pci_rebar_set_size() but by
pci_iov_resource_set_size(). pci_iov_resource_set_size() is called also
from pci_resize_resource_set_size().

The current arrangement is problematic once BAR resize algorithm starts to
roll back changes properly in case of a failure. The normal resource
fitting algorithm rolls back resource size using the struct
pci_dev_resource easily but also calling pci_resize_resource_set_size() or
pci_iov_resource_set_size() to roll back BAR size would be an extra burden,
whereas combining ->barsz[] update with pci_rebar_set_size() naturally
rolls back it when restoring the old BAR size on a different layer of the
BAR resize operation.

Thus, rework pci_rebar_set_size() to also update ->barsz[].

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
drivers/pci/iov.c | 15 ++++-----------
drivers/pci/pci.c | 4 ++++
drivers/pci/pci.h | 5 ++---
drivers/pci/setup-res.c | 10 ++++------
4 files changed, 14 insertions(+), 20 deletions(-)

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 77dee43b7858..04b675e90963 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -158,8 +158,7 @@ resource_size_t pci_iov_resource_size(struct pci_dev *dev, int resno)
return dev->sriov->barsz[pci_resource_num_to_vf_bar(resno)];
}

-void pci_iov_resource_set_size(struct pci_dev *dev, int resno,
- resource_size_t size)
+void pci_iov_resource_set_size(struct pci_dev *dev, int resno, int size)
{
if (!pci_resource_is_iov(resno)) {
pci_warn(dev, "%s is not an IOV resource\n",
@@ -167,7 +166,8 @@ void pci_iov_resource_set_size(struct pci_dev *dev, int resno,
return;
}

- dev->sriov->barsz[pci_resource_num_to_vf_bar(resno)] = size;
+ resno = pci_resource_num_to_vf_bar(resno);
+ dev->sriov->barsz[resno] = pci_rebar_size_to_bytes(size);
}

bool pci_iov_is_memory_decoding_enabled(struct pci_dev *dev)
@@ -1340,7 +1340,6 @@ EXPORT_SYMBOL_GPL(pci_sriov_configure_simple);
int pci_iov_vf_bar_set_size(struct pci_dev *dev, int resno, int size)
{
u32 sizes;
- int ret;

if (!pci_resource_is_iov(resno))
return -EINVAL;
@@ -1355,13 +1354,7 @@ int pci_iov_vf_bar_set_size(struct pci_dev *dev, int resno, int size)
if (!(sizes & BIT(size)))
return -EINVAL;

- ret = pci_rebar_set_size(dev, resno, size);
- if (ret)
- return ret;
-
- pci_iov_resource_set_size(dev, resno, pci_rebar_size_to_bytes(size));
-
- return 0;
+ return pci_rebar_set_size(dev, resno, size);
}
EXPORT_SYMBOL_GPL(pci_iov_vf_bar_set_size);

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b14dd064006c..7dfc58b0e55e 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3803,6 +3803,10 @@ int pci_rebar_set_size(struct pci_dev *pdev, int bar, int size)
ctrl &= ~PCI_REBAR_CTRL_BAR_SIZE;
ctrl |= FIELD_PREP(PCI_REBAR_CTRL_BAR_SIZE, size);
pci_write_config_dword(pdev, pos + PCI_REBAR_CTRL, ctrl);
+
+ if (pci_resource_is_iov(bar))
+ pci_iov_resource_set_size(pdev, bar, size);
+
return 0;
}

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 4492b809094b..bf1a577e9623 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -808,8 +808,7 @@ void pci_iov_update_resource(struct pci_dev *dev, int resno);
resource_size_t pci_sriov_resource_alignment(struct pci_dev *dev, int resno);
void pci_restore_iov_state(struct pci_dev *dev);
int pci_iov_bus_range(struct pci_bus *bus);
-void pci_iov_resource_set_size(struct pci_dev *dev, int resno,
- resource_size_t size);
+void pci_iov_resource_set_size(struct pci_dev *dev, int resno, int size);
bool pci_iov_is_memory_decoding_enabled(struct pci_dev *dev);
static inline u16 pci_iov_vf_rebar_cap(struct pci_dev *dev)
{
@@ -851,7 +850,7 @@ static inline int pci_iov_bus_range(struct pci_bus *bus)
return 0;
}
static inline void pci_iov_resource_set_size(struct pci_dev *dev, int resno,
- resource_size_t size) { }
+ int size) { }
static inline bool pci_iov_is_memory_decoding_enabled(struct pci_dev *dev)
{
return false;
diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index c3ba4ccecd43..3d0b0b3f60c4 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -450,12 +450,10 @@ static void pci_resize_resource_set_size(struct pci_dev *dev, int resno,
resource_size_t res_size = pci_rebar_size_to_bytes(size);
struct resource *res = pci_resource_n(dev, resno);

- if (!pci_resource_is_iov(resno)) {
- resource_set_size(res, res_size);
- } else {
- resource_set_size(res, res_size * pci_sriov_get_totalvfs(dev));
- pci_iov_resource_set_size(dev, resno, res_size);
- }
+ if (pci_resource_is_iov(resno))
+ res_size *= pci_sriov_get_totalvfs(dev);
+
+ resource_set_size(res, res_size);
}

int pci_resize_resource(struct pci_dev *dev, int resno, int size)
--
2.39.5