linux-kernel - [PATCH v3] PCI: Update Resizable BAR Capability Register fields

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Message-ID: <20250221010951.361570-1-daizhiyuan@phytium.com.cn>
Date: Fri, 21 Feb 2025 09:09:21 +0800
From: Zhiyuan Dai <daizhiyuan@...tium.com.cn>
To: cassel@...nel.org
Cc: bhelgaas@...gle.com,
	christian.koenig@....com,
	daizhiyuan@...tium.com.cn,
	helgaas@...nel.org,
	linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org
Subject: [PATCH v3] PCI: Update Resizable BAR Capability Register fields

PCI Express Base Spec r6.0 defines BAR size up to 8 EB (2^63 bytes),
but supporting anything bigger than 128TB requires changes to 
pci_rebar_get_possible_sizes() to read the additional Capability bits 
from the Control register.

If 8EB support is required, callers will need to be updated to handle u64 
instead of u32. For now, support is limited to 128TB, and support for 
sizes greater than 128TB can be deferred to a later time.

Signed-off-by: Zhiyuan Dai <daizhiyuan@...tium.com.cn>
Reviewed-by: Christian König <christian.koenig@....com>
Reviewed-by: Niklas Cassel <cassel@...nel.org>
---
 drivers/pci/pci.c             | 4 ++--
 include/uapi/linux/pci_regs.h | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 661f98c6c63a..77b9ceefb4e1 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3752,7 +3752,7 @@ static int pci_rebar_find_pos(struct pci_dev *pdev, int bar)
  * @bar: BAR to query
  *
  * Get the possible sizes of a resizable BAR as bitmask defined in the spec
- * (bit 0=1MB, bit 19=512GB). Returns 0 if BAR isn't resizable.
+ * (bit 0=1MB, bit 31=128TB). Returns 0 if BAR isn't resizable.
  */
 u32 pci_rebar_get_possible_sizes(struct pci_dev *pdev, int bar)
 {
@@ -3800,7 +3800,7 @@ int pci_rebar_get_current_size(struct pci_dev *pdev, int bar)
  * pci_rebar_set_size - set a new size for a BAR
  * @pdev: PCI device
  * @bar: BAR to set size to
- * @size: new size as defined in the spec (0=1MB, 19=512GB)
+ * @size: new size as defined in the spec (0=1MB, 31=128TB)
  *
  * Set the new size of a BAR as defined in the spec.
  * Returns zero if resizing was successful, error code otherwise.
diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index 1601c7ed5fab..ce99d4f34ce5 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -1013,7 +1013,7 @@
 
 /* Resizable BARs */
 #define PCI_REBAR_CAP		4	/* capability register */
-#define  PCI_REBAR_CAP_SIZES		0x00FFFFF0  /* supported BAR sizes */
+#define  PCI_REBAR_CAP_SIZES		0xFFFFFFF0  /* supported BAR sizes */
 #define PCI_REBAR_CTRL		8	/* control register */
 #define  PCI_REBAR_CTRL_BAR_IDX		0x00000007  /* BAR index */
 #define  PCI_REBAR_CTRL_NBAR_MASK	0x000000E0  /* # of resizable BARs */
-- 
2.43.0