Re: [RFC PATCH 1/3] PCI: endpoint: support an alignment aware map/unmaping

From: Shunsuke Mie
Date: Wed Jan 18 2023 - 06:22:15 EST


On 2023/01/18 5:41, Bjorn Helgaas wrote:
On Fri, Jan 13, 2023 at 06:03:48PM +0900, Shunsuke Mie wrote:
Add an align_mem operation to the EPC ops, which function is used to
pci_epc_map/unmap_addr(). These change to enable mapping for any alignment
restriction of EPC. The map function maps an aligned memory to include a
requested memory region.
I think this does two things: 1) add the .align_mem() function
pointer, and 2) move the pci_epc_mem_alloc_addr() call into
pci_epc_map_addr(). For 2), I would expect to see
pci_epc_mem_alloc_addr() being *removed* from somewhere else.

Anyway, both are significant and should be mentioned in the commit
log. Possibly they could even be separate commits: move the
alloc/free first, then add .align_mem().
I understood. I attempt to arrange commits as your mention.

Another question below.

Signed-off-by: Shunsuke Mie <mie@xxxxxxxxxx>
---
drivers/pci/endpoint/pci-epc-core.c | 57 ++++++++++++++++++++++++-----
include/linux/pci-epc.h | 10 +++--
2 files changed, 53 insertions(+), 14 deletions(-)

diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index 2542196e8c3d..60d586e05e7d 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -430,8 +430,12 @@ EXPORT_SYMBOL_GPL(pci_epc_set_msix);
* Invoke to unmap the CPU address from PCI address.
*/
void pci_epc_unmap_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
- phys_addr_t phys_addr)
+ phys_addr_t phys_addr, void __iomem *virt_addr, size_t size)
{
+ u64 aligned_phys;
+ void __iomem *aligned_virt;
+ size_t offset;
+
if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions)
return;
@@ -441,9 +445,22 @@ void pci_epc_unmap_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
if (!epc->ops->unmap_addr)
return;
+ if (epc->ops->align_mem) {
+ mutex_lock(&epc->lock);
+ aligned_phys = epc->ops->align_mem(epc, phys_addr, &size);
+ mutex_unlock(&epc->lock);
+ } else {
+ aligned_phys = phys_addr;
+ }
+
+ offset = phys_addr - aligned_phys;
+ aligned_virt = virt_addr - offset;
+
mutex_lock(&epc->lock);
- epc->ops->unmap_addr(epc, func_no, vfunc_no, phys_addr);
+ epc->ops->unmap_addr(epc, func_no, vfunc_no, aligned_phys);
mutex_unlock(&epc->lock);
+
+ pci_epc_mem_free_addr(epc, aligned_phys, aligned_virt, size);
}
EXPORT_SYMBOL_GPL(pci_epc_unmap_addr);
@@ -458,26 +475,46 @@ EXPORT_SYMBOL_GPL(pci_epc_unmap_addr);
*
* Invoke to map CPU address with PCI address.
*/
-int pci_epc_map_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
- phys_addr_t phys_addr, u64 pci_addr, size_t size)
+void __iomem *pci_epc_map_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+ u64 pci_addr, phys_addr_t *phys_addr, size_t size)
{
int ret;
+ u64 aligned_addr;
+ size_t offset;
+ void __iomem *virt_addr;
if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions)
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
if (vfunc_no > 0 && (!epc->max_vfs || vfunc_no > epc->max_vfs[func_no]))
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
if (!epc->ops->map_addr)
- return 0;
+ return ERR_PTR(-ENOPTSUPP);
+
+ if (epc->ops->align_mem) {
+ mutex_lock(&epc->lock);
+ aligned_addr = epc->ops->align_mem(epc, pci_addr, &size);
+ mutex_unlock(&epc->lock);
+ } else {
+ aligned_addr = pci_addr;
+ }
+
+ offset = pci_addr - aligned_addr;
+
+ virt_addr = pci_epc_mem_alloc_addr(epc, phys_addr, size);
+ if (!virt_addr)
+ return ERR_PTR(-ENOMEM);
mutex_lock(&epc->lock);
- ret = epc->ops->map_addr(epc, func_no, vfunc_no, phys_addr, pci_addr,
- size);
+ ret = epc->ops->map_addr(epc, func_no, vfunc_no, *phys_addr, aligned_addr, size);
mutex_unlock(&epc->lock);
+ if (ret)
+ return ERR_PTR(ret);
- return ret;
+ *phys_addr += offset;
+
+ return virt_addr + offset;
}
EXPORT_SYMBOL_GPL(pci_epc_map_addr);
diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index a48778e1a4ee..8f29161bce80 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -84,6 +84,7 @@ struct pci_epc_ops {
phys_addr_t phys_addr, u8 interrupt_num,
u32 entry_size, u32 *msi_data,
u32 *msi_addr_offset);
+ u64 (*align_mem)(struct pci_epc *epc, u64 addr, size_t *size);
Is there a requirement for multiple implementations of .align_mem()?
There's only one implementation in this series
(dw_pcie_ep_align_mem()), and it only needs pci->region_align. That
*value* might be DWC-specific, but the concept really isn't, so maybe
there could be a generic function that uses the device-specific value.

That is the correct way, but some handlers require different implementation.

Sorry, this patch could have been misleading. it is my fault. I'll add the other

handlers to a next version.


int (*start)(struct pci_epc *epc);
void (*stop)(struct pci_epc *epc);
const struct pci_epc_features* (*get_features)(struct pci_epc *epc,
@@ -218,11 +219,12 @@ int pci_epc_set_bar(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
struct pci_epf_bar *epf_bar);
void pci_epc_clear_bar(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
struct pci_epf_bar *epf_bar);
-int pci_epc_map_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
- phys_addr_t phys_addr,
- u64 pci_addr, size_t size);
+void __iomem *pci_epc_map_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
+ u64 pci_addr, phys_addr_t *phys_addr,
+ size_t size);
void pci_epc_unmap_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
- phys_addr_t phys_addr);
+ phys_addr_t phys_addr, void __iomem *virt_addr,
+ size_t size);
int pci_epc_set_msi(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
u8 interrupts);
int pci_epc_get_msi(struct pci_epc *epc, u8 func_no, u8 vfunc_no);
--
2.25.1

Best,

Shunsuke