Re: [PATCH] PCI: endpoint: Migrate to Genalloc framework for outbound window memory allocation
From: Frank Li
Date: Tue Mar 19 2024 - 11:51:15 EST
On Sun, Mar 17, 2024 at 11:39:17AM +0530, Manivannan Sadhasivam wrote:
> As proposed during the last year 'PCI Endpoint Subsystem Open Items
> Discussion' of Linux Plumbers conference [1], let's migrate to Genalloc
> framework for managing the endpoint outbound window memory allocation.
>
> PCI Endpoint subsystem is using a custom memory allocator in pci-epc-mem
> driver from the start for managing the memory required to map the host
> address space (outbound) in endpoint. Even though it works well, it
> completely defeats the purpose of the 'Genalloc framework', a general
> purpose memory allocator framework created to avoid various custom memory
> allocators in the kernel.
>
> The migration to Genalloc framework is done is such a way that the existing
> API semantics are preserved. So that the callers of the EPC mem APIs do not
> need any modification (apart from the pcie-designware-epc driver that
> queries page size).
>
> Internally, the EPC mem driver now uses Genalloc framework's
> 'gen_pool_first_fit_order_align' algorithm that aligns the allocated memory
> based on the requested size as like the previous allocator. And the
> page size passed during pci_epc_mem_init() API is used as the minimum order
> for the memory allocations.
>
> During the migration, 'struct pci_epc_mem' is removed as it is seems
> redundant and the existing 'struct pci_epc_mem_window' in 'struct pci_epc'
> is now used to hold the address windows of the endpoint controller.
>
> [1] https://lpc.events/event/17/contributions/1419/
>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> ---
> drivers/pci/controller/dwc/pcie-designware-ep.c | 14 +-
> drivers/pci/endpoint/pci-epc-mem.c | 182 +++++++++---------------
> include/linux/pci-epc.h | 25 +---
> 3 files changed, 81 insertions(+), 140 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index 5befed2dc02b..37c612282eb6 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -482,11 +482,11 @@ int dw_pcie_ep_raise_msi_irq(struct dw_pcie_ep *ep, u8 func_no,
> reg = ep_func->msi_cap + PCI_MSI_DATA_32;
> msg_data = dw_pcie_ep_readw_dbi(ep, func_no, reg);
> }
> - aligned_offset = msg_addr_lower & (epc->mem->window.page_size - 1);
> + aligned_offset = msg_addr_lower & (epc->windows[0]->page_size - 1);
> msg_addr = ((u64)msg_addr_upper) << 32 |
> (msg_addr_lower & ~aligned_offset);
> ret = dw_pcie_ep_map_addr(epc, func_no, 0, ep->msi_mem_phys, msg_addr,
> - epc->mem->window.page_size);
> + epc->windows[0]->page_size);
> if (ret)
> return ret;
>
> @@ -550,10 +550,10 @@ int dw_pcie_ep_raise_msix_irq(struct dw_pcie_ep *ep, u8 func_no,
> return -EPERM;
> }
>
> - aligned_offset = msg_addr & (epc->mem->window.page_size - 1);
> + aligned_offset = msg_addr & (epc->windows[0]->page_size - 1);
> msg_addr &= ~aligned_offset;
> ret = dw_pcie_ep_map_addr(epc, func_no, 0, ep->msi_mem_phys, msg_addr,
> - epc->mem->window.page_size);
> + epc->windows[0]->page_size);
> if (ret)
> return ret;
>
> @@ -572,7 +572,7 @@ void dw_pcie_ep_exit(struct dw_pcie_ep *ep)
> dw_pcie_edma_remove(pci);
>
> pci_epc_mem_free_addr(epc, ep->msi_mem_phys, ep->msi_mem,
> - epc->mem->window.page_size);
> + epc->windows[0]->page_size);
>
> pci_epc_mem_exit(epc);
>
> @@ -742,7 +742,7 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
> }
>
> ep->msi_mem = pci_epc_mem_alloc_addr(epc, &ep->msi_mem_phys,
> - epc->mem->window.page_size);
> + epc->windows[0]->page_size);
> if (!ep->msi_mem) {
> ret = -ENOMEM;
> dev_err(dev, "Failed to reserve memory for MSI/MSI-X\n");
> @@ -770,7 +770,7 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
>
> err_free_epc_mem:
> pci_epc_mem_free_addr(epc, ep->msi_mem_phys, ep->msi_mem,
> - epc->mem->window.page_size);
> + epc->windows[0]->page_size);
>
> err_exit_epc_mem:
> pci_epc_mem_exit(epc);
> diff --git a/drivers/pci/endpoint/pci-epc-mem.c b/drivers/pci/endpoint/pci-epc-mem.c
> index a9c028f58da1..f9e6e1a6aeaa 100644
> --- a/drivers/pci/endpoint/pci-epc-mem.c
> +++ b/drivers/pci/endpoint/pci-epc-mem.c
> @@ -4,37 +4,18 @@
> *
> * Copyright (C) 2017 Texas Instruments
> * Author: Kishon Vijay Abraham I <kishon@xxxxxx>
> + *
> + * Copyright (C) 2024 Linaro Ltd.
> + * Author: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> */
>
> +#include <linux/genalloc.h>
> #include <linux/io.h>
> #include <linux/module.h>
> #include <linux/slab.h>
>
> #include <linux/pci-epc.h>
>
> -/**
> - * pci_epc_mem_get_order() - determine the allocation order of a memory size
> - * @mem: address space of the endpoint controller
> - * @size: the size for which to get the order
> - *
> - * Reimplement get_order() for mem->page_size since the generic get_order
> - * always gets order with a constant PAGE_SIZE.
> - */
> -static int pci_epc_mem_get_order(struct pci_epc_mem *mem, size_t size)
> -{
> - int order;
> - unsigned int page_shift = ilog2(mem->window.page_size);
> -
> - size--;
> - size >>= page_shift;
> -#if BITS_PER_LONG == 32
> - order = fls(size);
> -#else
> - order = fls64(size);
> -#endif
> - return order;
> -}
> -
> /**
> * pci_epc_multi_mem_init() - initialize the pci_epc_mem structure
> * @epc: the EPC device that invoked pci_epc_mem_init
> @@ -48,17 +29,11 @@ int pci_epc_multi_mem_init(struct pci_epc *epc,
> struct pci_epc_mem_window *windows,
> unsigned int num_windows)
> {
> - struct pci_epc_mem *mem = NULL;
> - unsigned long *bitmap = NULL;
> - unsigned int page_shift;
> + struct pci_epc_mem_window *window = NULL;
> size_t page_size;
> - int bitmap_size;
> - int pages;
> int ret;
> int i;
>
> - epc->num_windows = 0;
> -
> if (!windows || !num_windows)
> return -EINVAL;
>
> @@ -70,45 +45,51 @@ int pci_epc_multi_mem_init(struct pci_epc *epc,
> page_size = windows[i].page_size;
> if (page_size < PAGE_SIZE)
> page_size = PAGE_SIZE;
> - page_shift = ilog2(page_size);
> - pages = windows[i].size >> page_shift;
> - bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
>
> - mem = kzalloc(sizeof(*mem), GFP_KERNEL);
> - if (!mem) {
> + windows[i].pool = gen_pool_create(ilog2(page_size), -1);
I think it is not good to modify caller's memory. This funciton suppose
pass down read-only information. And set to epc->windows[i]. I think it'd
better to use epc->windows[i].pool/windows.
> + if (!windows[i].pool) {
> ret = -ENOMEM;
> - i--;
> - goto err_mem;
> + goto err_free_mem;
> + }
> +
> + gen_pool_set_algo(windows[i].pool, gen_pool_first_fit_order_align,
> + NULL);
> +
> + windows[i].virt_base = ioremap(windows[i].phys_base, windows[i].size);
> + ret = gen_pool_add_virt(windows[i].pool, (unsigned long)windows[i].virt_base,
> + windows[i].phys_base, windows[i].size, -1);
> + if (ret) {
> + iounmap(windows[i].virt_base);
> + gen_pool_destroy(epc->windows[i]->pool);
I think move all free to err path will be easy to understand.
> + goto err_free_mem;
> }
>
> - bitmap = kzalloc(bitmap_size, GFP_KERNEL);
> - if (!bitmap) {
> + window = kzalloc(sizeof(*window), GFP_KERNEL);
According to below code
epc->windows = kcalloc(num_windows, sizeof(*epc->windows), GFP_KERNEL);
if (!epc->windows)
return -ENOMEM;
epc->windows already allocate whole num_windows * "struct pci_epc_mem_window".
I think you can direct use 'window = epc->windows + i', so needn't alloc
additional memory for epc->windows[i].
> + if (!window) {
> ret = -ENOMEM;
> - kfree(mem);
> - i--;
> - goto err_mem;
> + iounmap(windows[i].virt_base);
> + gen_pool_destroy(epc->windows[i]->pool);
> + goto err_free_mem;
> }
>
> - mem->window.phys_base = windows[i].phys_base;
> - mem->window.size = windows[i].size;
> - mem->window.page_size = page_size;
> - mem->bitmap = bitmap;
> - mem->pages = pages;
> - mutex_init(&mem->lock);
> - epc->windows[i] = mem;
> + window->phys_base = windows[i].phys_base;
> + window->size = windows[i].size;
> + window->page_size = page_size;
> + window->pool = windows[i].pool;
> + epc->windows[i] = window;
> }
>
> - epc->mem = epc->windows[0];
> epc->num_windows = num_windows;
>
> return 0;
>
> -err_mem:
> - for (; i >= 0; i--) {
> - mem = epc->windows[i];
> - kfree(mem->bitmap);
> - kfree(mem);
> +err_free_mem:
> + for (--i; i >= 0; i--) {
> + iounmap(windows[i].virt_base);
> + gen_pool_destroy(epc->windows[i]->pool);
> + kfree(epc->windows[i]);
> }
> +
> kfree(epc->windows);
>
> return ret;
> @@ -128,14 +109,15 @@ EXPORT_SYMBOL_GPL(pci_epc_multi_mem_init);
> int pci_epc_mem_init(struct pci_epc *epc, phys_addr_t base,
> size_t size, size_t page_size)
> {
> - struct pci_epc_mem_window mem_window;
> + struct pci_epc_mem_window window;
>
> - mem_window.phys_base = base;
> - mem_window.size = size;
> - mem_window.page_size = page_size;
> + window.phys_base = base;
> + window.size = size;
> + window.page_size = page_size;
>
> - return pci_epc_multi_mem_init(epc, &mem_window, 1);
> + return pci_epc_multi_mem_init(epc, &window, 1);
> }
> +
Remove extra empty line change
> EXPORT_SYMBOL_GPL(pci_epc_mem_init);
>
> /**
> @@ -147,21 +129,20 @@ EXPORT_SYMBOL_GPL(pci_epc_mem_init);
> */
> void pci_epc_mem_exit(struct pci_epc *epc)
> {
> - struct pci_epc_mem *mem;
> int i;
>
> if (!epc->num_windows)
> return;
>
> for (i = 0; i < epc->num_windows; i++) {
> - mem = epc->windows[i];
> - kfree(mem->bitmap);
> - kfree(mem);
> + iounmap(epc->windows[i]->virt_base);
> + gen_pool_destroy(epc->windows[i]->pool);
> + kfree(epc->windows[i]);
> }
> +
> kfree(epc->windows);
>
> epc->windows = NULL;
> - epc->mem = NULL;
> epc->num_windows = 0;
> }
> EXPORT_SYMBOL_GPL(pci_epc_mem_exit);
> @@ -178,55 +159,42 @@ EXPORT_SYMBOL_GPL(pci_epc_mem_exit);
> void __iomem *pci_epc_mem_alloc_addr(struct pci_epc *epc,
> phys_addr_t *phys_addr, size_t size)
> {
> + struct pci_epc_mem_window *window;
> void __iomem *virt_addr = NULL;
> - struct pci_epc_mem *mem;
> - unsigned int page_shift;
> + struct gen_pool *genpool;
> size_t align_size;
> - int pageno;
> - int order;
> int i;
>
> for (i = 0; i < epc->num_windows; i++) {
> - mem = epc->windows[i];
> - mutex_lock(&mem->lock);
> - align_size = ALIGN(size, mem->window.page_size);
> - order = pci_epc_mem_get_order(mem, align_size);
> -
> - pageno = bitmap_find_free_region(mem->bitmap, mem->pages,
> - order);
> - if (pageno >= 0) {
> - page_shift = ilog2(mem->window.page_size);
> - *phys_addr = mem->window.phys_base +
> - ((phys_addr_t)pageno << page_shift);
> - virt_addr = ioremap(*phys_addr, align_size);
> - if (!virt_addr) {
> - bitmap_release_region(mem->bitmap,
> - pageno, order);
> - mutex_unlock(&mem->lock);
> - continue;
> - }
> - mutex_unlock(&mem->lock);
> - return virt_addr;
> - }
> - mutex_unlock(&mem->lock);
> + window = epc->windows[i];
> + genpool = window->pool;
> + align_size = ALIGN(size, window->page_size);
> +
> + virt_addr = (void __iomem *)gen_pool_alloc(genpool, align_size);
> + if (!virt_addr)
> + continue;
> +
> + *phys_addr = gen_pool_virt_to_phys(genpool, (unsigned long)virt_addr);
> +
> + break;
> }
>
> return virt_addr;
> }
> EXPORT_SYMBOL_GPL(pci_epc_mem_alloc_addr);
>
> -static struct pci_epc_mem *pci_epc_get_matching_window(struct pci_epc *epc,
> +static struct pci_epc_mem_window *pci_epc_get_matching_window(struct pci_epc *epc,
> phys_addr_t phys_addr)
> {
> - struct pci_epc_mem *mem;
> + struct pci_epc_mem_window *window;
> int i;
>
> for (i = 0; i < epc->num_windows; i++) {
> - mem = epc->windows[i];
> + window = epc->windows[i];
>
> - if (phys_addr >= mem->window.phys_base &&
> - phys_addr < (mem->window.phys_base + mem->window.size))
> - return mem;
> + if (phys_addr >= window->phys_base &&
> + phys_addr < (window->phys_base + window->size))
> + return window;
> }
>
> return NULL;
> @@ -244,27 +212,15 @@ static struct pci_epc_mem *pci_epc_get_matching_window(struct pci_epc *epc,
> void pci_epc_mem_free_addr(struct pci_epc *epc, phys_addr_t phys_addr,
> void __iomem *virt_addr, size_t size)
> {
> - struct pci_epc_mem *mem;
> - unsigned int page_shift;
> - size_t page_size;
> - int pageno;
> - int order;
> + struct pci_epc_mem_window *window;
>
> - mem = pci_epc_get_matching_window(epc, phys_addr);
> - if (!mem) {
> + window = pci_epc_get_matching_window(epc, phys_addr);
> + if (!window) {
> pr_err("failed to get matching window\n");
> return;
> }
>
> - page_size = mem->window.page_size;
> - page_shift = ilog2(page_size);
> - iounmap(virt_addr);
> - pageno = (phys_addr - mem->window.phys_base) >> page_shift;
> - size = ALIGN(size, page_size);
> - order = pci_epc_mem_get_order(mem, size);
> - mutex_lock(&mem->lock);
> - bitmap_release_region(mem->bitmap, pageno, order);
> - mutex_unlock(&mem->lock);
> + gen_pool_free(window->pool, (unsigned long)virt_addr, size);
> }
> EXPORT_SYMBOL_GPL(pci_epc_mem_free_addr);
>
> diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
> index 40ea18f5aa02..37ea96ed3432 100644
> --- a/include/linux/pci-epc.h
> +++ b/include/linux/pci-epc.h
> @@ -87,30 +87,19 @@ struct pci_epc_ops {
> /**
> * struct pci_epc_mem_window - address window of the endpoint controller
> * @phys_base: physical base address of the PCI address window
> + * @virt_base: virtual base address of the PCI address window
> + * @pool: memory pool descriptor
> * @size: the size of the PCI address window
> * @page_size: size of each page
> */
> struct pci_epc_mem_window {
> phys_addr_t phys_base;
> + void __iomem *virt_base;
> + struct gen_pool *pool;
> size_t size;
> size_t page_size;
> };
>
> -/**
> - * struct pci_epc_mem - address space of the endpoint controller
> - * @window: address window of the endpoint controller
> - * @bitmap: bitmap to manage the PCI address space
> - * @pages: number of bits representing the address region
> - * @lock: mutex to protect bitmap
> - */
> -struct pci_epc_mem {
> - struct pci_epc_mem_window window;
> - unsigned long *bitmap;
> - int pages;
> - /* mutex to protect against concurrent access for memory allocation*/
> - struct mutex lock;
> -};
> -
> /**
> * struct pci_epc - represents the PCI EPC device
> * @dev: PCI EPC device
> @@ -118,9 +107,6 @@ struct pci_epc_mem {
> * @list_lock: Mutex for protecting pci_epf list
> * @ops: function pointers for performing endpoint operations
> * @windows: array of address space of the endpoint controller
> - * @mem: first window of the endpoint controller, which corresponds to
> - * default address space of the endpoint controller supporting
> - * single window.
> * @num_windows: number of windows supported by device
> * @max_functions: max number of functions that can be configured in this EPC
> * @max_vfs: Array indicating the maximum number of virtual functions that can
> @@ -134,8 +120,7 @@ struct pci_epc {
> struct list_head pci_epf;
> struct mutex list_lock;
> const struct pci_epc_ops *ops;
> - struct pci_epc_mem **windows;
> - struct pci_epc_mem *mem;
> + struct pci_epc_mem_window **windows;
> unsigned int num_windows;
> u8 max_functions;
> u8 *max_vfs;
>
> ---
> base-commit: 256833a66670ff28b7c1bddbd17973619e5281fd
> change-id: 20240317-pci-ep-genalloc-fa89f5e487e3
>
> Best regards,
> --
> Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
>