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PCI/IOV: Allow IOV resources to be resized in pci_resize_resource()

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Similar to regular resizable BARs, VF BARs can also be resized.

The capability layout is the same as PCI_EXT_CAP_ID_REBAR, which means we
can reuse most of the implementation, the only difference being resource
size calculation (which is multiplied by total VFs) and memory decoding
(which is controlled by a separate VF MSE field in SR-IOV cap).

Extend the pci_resize_resource() function to accept IOV resources.

See PCIe r6.2, sec 7.8.7.

Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://patch.msgid.link/20250702093522.518099-4-michal.winiarski@intel.com
This commit is contained in:
Michał Winiarski 2025-07-02 11:35:20 +02:00 • committed by Bjorn Helgaas
parent 535bdbeaac
commit e200f4f7ea
4 changed files with 67 additions and 6 deletions
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21
drivers/pci/iov.c
View file

@ -154,6 +154,27 @@ 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)
{
if (!pci_resource_is_iov(resno)) {
pci_warn(dev, "%s is not an IOV resource\n",
pci_resource_name(dev, resno));
return;
}
dev->sriov->barsz[pci_resource_num_to_vf_bar(resno)] = size;
}
bool pci_iov_is_memory_decoding_enabled(struct pci_dev *dev)
{
u16 cmd;
pci_read_config_word(dev, dev->sriov->pos + PCI_SRIOV_CTRL, &cmd);
return cmd & PCI_SRIOV_CTRL_MSE;
}
static void pci_read_vf_config_common(struct pci_dev *virtfn)
{
struct pci_dev *physfn = virtfn->physfn;

8
drivers/pci/pci.c
View file

@ -3752,7 +3752,13 @@ static int pci_rebar_find_pos(struct pci_dev *pdev, int bar)
unsigned int pos, nbars, i;
u32 ctrl;
pos = pdev->rebar_cap;
if (pci_resource_is_iov(bar)) {
pos = pci_iov_vf_rebar_cap(pdev);
bar = pci_resource_num_to_vf_bar(bar);
} else {
pos = pdev->rebar_cap;
}
if (!pos)
return -ENOTSUPP;

9
drivers/pci/pci.h
View file

@ -711,6 +711,9 @@ 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);
bool pci_iov_is_memory_decoding_enabled(struct pci_dev *dev);
static inline u16 pci_iov_vf_rebar_cap(struct pci_dev *dev)
{
if (!dev->is_physfn)
@ -750,6 +753,12 @@ 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) { }
static inline bool pci_iov_is_memory_decoding_enabled(struct pci_dev *dev)
{
return false;
}
static inline u16 pci_iov_vf_rebar_cap(struct pci_dev *dev)
{
return 0;

35
drivers/pci/setup-res.c
View file

@ -423,13 +423,39 @@ void pci_release_resource(struct pci_dev *dev, int resno)
}
EXPORT_SYMBOL(pci_release_resource);
static bool pci_resize_is_memory_decoding_enabled(struct pci_dev *dev,
int resno)
{
u16 cmd;
if (pci_resource_is_iov(resno))
return pci_iov_is_memory_decoding_enabled(dev);
pci_read_config_word(dev, PCI_COMMAND, &cmd);
return cmd & PCI_COMMAND_MEMORY;
}
static void pci_resize_resource_set_size(struct pci_dev *dev, int resno,
int size)
{
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);
}
}
int pci_resize_resource(struct pci_dev *dev, int resno, int size)
{
struct resource *res = pci_resource_n(dev, resno);
struct pci_host_bridge *host;
int old, ret;
u32 sizes;
u16 cmd;
/* Check if we must preserve the firmware's resource assignment */
host = pci_find_host_bridge(dev->bus);
@ -440,8 +466,7 @@ int pci_resize_resource(struct pci_dev *dev, int resno, int size)
if (!(res->flags & IORESOURCE_UNSET))
return -EBUSY;
pci_read_config_word(dev, PCI_COMMAND, &cmd);
if (cmd & PCI_COMMAND_MEMORY)
if (pci_resize_is_memory_decoding_enabled(dev, resno))
return -EBUSY;
sizes = pci_rebar_get_possible_sizes(dev, resno);
@ -459,7 +484,7 @@ int pci_resize_resource(struct pci_dev *dev, int resno, int size)
if (ret)
return ret;
resource_set_size(res, pci_rebar_size_to_bytes(size));
pci_resize_resource_set_size(dev, resno, size);
/* Check if the new config works by trying to assign everything. */
if (dev->bus->self) {
@ -471,7 +496,7 @@ int pci_resize_resource(struct pci_dev *dev, int resno, int size)
error_resize:
pci_rebar_set_size(dev, resno, old);
resource_set_size(res, pci_rebar_size_to_bytes(old));
pci_resize_resource_set_size(dev, resno, old);
return ret;
}
EXPORT_SYMBOL(pci_resize_resource);