Drivers could leverage the fact that the VF BAR MMIO reservation is
created for total number of VFs supported by the device by resizing the
BAR to larger size when smaller number of VFs is enabled.
Add a pci_iov_vf_bar_set_size() function to control the size and a
pci_iov_vf_bar_get_sizes() helper to get the VF BAR sizes that will
allow up to num_vfs to be successfully enabled with the current
underlying reservation size.
Signed-off-by: Michał Winiarski <michal.winiar...@intel.com>
---
drivers/pci/iov.c | 73 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/pci.h | 6 ++++
2 files changed, 79 insertions(+)
diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index f34173c70b32a..ac4375954c947 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -8,11 +8,15 @@
*/
#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/log2.h>
#include <linux/pci.h>
+#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/string.h>
#include <linux/delay.h>
+#include <asm/div64.h>
#include "pci.h"
#define VIRTFN_ID_LEN 17 /* "virtfn%u\0" for 2^32 - 1 */
@@ -1313,3 +1317,72 @@ int pci_sriov_configure_simple(struct pci_dev *dev, int
nr_virtfn)
return nr_virtfn;
}
EXPORT_SYMBOL_GPL(pci_sriov_configure_simple);
+
+/**
+ * pci_iov_vf_bar_set_size - set a new size for a VF BAR
+ * @dev: the PCI device
+ * @resno: the resource number
+ * @size: new size as defined in the spec (0=1MB, 31=128TB)
+ *
+ * Set the new size of a VF BAR that supports VF resizable BAR capability.
+ * Unlike pci_resize_resource(), this does not cause the resource that
+ * reserves the MMIO space (originally up to total_VFs) to be resized, which
+ * means that following calls to pci_enable_sriov() can fail if the resources
+ * no longer fit.
+ *
+ * Return: 0 on success, or negative on failure.
+ */
+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;
+
+ if (pci_iov_is_memory_decoding_enabled(dev))
+ return -EBUSY;
+
+ sizes = pci_rebar_get_possible_sizes(dev, resno);
+ if (!sizes)
+ return -ENOTSUPP;
+
+ 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;
+}
+EXPORT_SYMBOL_GPL(pci_iov_vf_bar_set_size);
+
+/**
+ * pci_iov_vf_bar_get_sizes - get VF BAR sizes allowing to create up to num_vfs
+ * @dev: the PCI device
+ * @resno: the resource number
+ * @num_vfs: number of VFs
+ *
+ * Get the sizes of a VF resizable BAR that can accommodate @num_vfs within
+ * the currently assigned size of the resource @resno.
+ *
+ * Return: A bitmask of sizes in format defined in the spec (bit 0=1MB,
+ * bit 31=128TB).
+ */
+u32 pci_iov_vf_bar_get_sizes(struct pci_dev *dev, int resno, int num_vfs)
+{
+ u64 vf_len = pci_resource_len(dev, resno);
+ u32 sizes;
+
+ if (!num_vfs)
+ return 0;
+
+ do_div(vf_len, num_vfs);
+ sizes = (roundup_pow_of_two(vf_len + 1) - 1) >> ilog2(SZ_1M);
+
+ return sizes & pci_rebar_get_possible_sizes(dev, resno);
+}
+EXPORT_SYMBOL_GPL(pci_iov_vf_bar_get_sizes);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index ab62bcb5f99c6..cc633b1a13d51 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2437,6 +2437,8 @@ int pci_sriov_set_totalvfs(struct pci_dev *dev, u16
numvfs);
int pci_sriov_get_totalvfs(struct pci_dev *dev);
int pci_sriov_configure_simple(struct pci_dev *dev, int nr_virtfn);
resource_size_t pci_iov_resource_size(struct pci_dev *dev, int resno);
+int pci_iov_vf_bar_set_size(struct pci_dev *dev, int resno, int size);
+u32 pci_iov_vf_bar_get_sizes(struct pci_dev *dev, int resno, int num_vfs);
void pci_vf_drivers_autoprobe(struct pci_dev *dev, bool probe);
/* Arch may override these (weak) */
@@ -2489,6 +2491,10 @@ static inline int pci_sriov_get_totalvfs(struct pci_dev
*dev)
#define pci_sriov_configure_simple NULL
static inline resource_size_t pci_iov_resource_size(struct pci_dev *dev, int
resno)
{ return 0; }
+static inline int pci_iov_vf_bar_set_size(struct pci_dev *dev, int resno, int
size)
+{ return -ENODEV; }
+static inline u32 pci_iov_vf_bar_get_sizes(struct pci_dev *dev, int resno, int
num_vfs)
+{ return 0; }
static inline void pci_vf_drivers_autoprobe(struct pci_dev *dev, bool probe) {
}
#endif
--
2.49.0
