| Message ID | 20250407-pci-ep-size-alignment-v3-2-865878e68cc8@baylibre.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | PCI: endpoint: space allocation fixups | expand |
Hello Jerome, On Mon, Apr 07, 2025 at 04:39:08PM +0200, Jerome Brunet wrote: > When trying to allocate space for an endpoint function on a BAR with a > fixed size, the size saved in the 'struct pci_epf_bar' should be the fixed > size. This is expected by pci_epc_set_bar(). > > However, if the fixed_size is smaller that the alignment, the size saved > in the 'struct pci_epf_bar' matches the alignment and it is a problem for > pci_epc_set_bar(). > > To solve this, continue to allocate space that match the iATU alignment > requirement but save the size that matches what is present in the BAR. > > Fixes: 2a9a801620ef ("PCI: endpoint: Add support to specify alignment for buffers allocated to BARs") > Signed-off-by: Jerome Brunet <jbrunet@baylibre.com> > --- > drivers/pci/endpoint/pci-epf-core.c | 25 +++++++++++++++++-------- > 1 file changed, 17 insertions(+), 8 deletions(-) > > diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c > index b7deb0ee1760b23a24f49abf3baf53ea2f273476..fb902b751e1c965c902c5199d57969ae0a757c2e 100644 > --- a/drivers/pci/endpoint/pci-epf-core.c > +++ b/drivers/pci/endpoint/pci-epf-core.c > @@ -225,6 +225,7 @@ void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar, > struct device *dev; > struct pci_epf_bar *epf_bar; > struct pci_epc *epc; > + size_t size; > > if (!addr) > return; > @@ -237,9 +238,12 @@ void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar, > epf_bar = epf->sec_epc_bar; > } > > + size = epf_bar[bar].size; > + if (epc_features->align) > + size = ALIGN(size, epc_features->align); Personally, I think that you should just save the aligned_size / mem_size / backing_mem_size as a new struct member, as that avoids the risk that someone later modifies pci_epf_alloc_space() but forgets to update pci_epf_free_space() accordingly. But I will leave the decision to the PCI endpoint maintainers. Kind regards, Niklas > + > dev = epc->dev.parent; > - dma_free_coherent(dev, epf_bar[bar].size, addr, > - epf_bar[bar].phys_addr); > + dma_free_coherent(dev, size, addr, epf_bar[bar].phys_addr); > > epf_bar[bar].phys_addr = 0; > epf_bar[bar].addr = NULL; > @@ -266,7 +270,7 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar, > enum pci_epc_interface_type type) > { > u64 bar_fixed_size = epc_features->bar[bar].fixed_size; > - size_t align = epc_features->align; > + size_t aligned_size, align = epc_features->align; > struct pci_epf_bar *epf_bar; > dma_addr_t phys_addr; > struct pci_epc *epc; > @@ -287,12 +291,17 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar, > return NULL; > } > size = bar_fixed_size; > + } else { > + /* BAR size must be power of two */ > + size = roundup_pow_of_two(size); > } > > - if (align) > - size = ALIGN(size, align); > - else > - size = roundup_pow_of_two(size); > + /* > + * Allocate enough memory to accommodate the iATU alignment requirement. > + * In most cases, this will be the same as .size but it might be different > + * if, for example, the fixed size of a BAR is smaller than align > + */ > + aligned_size = align ? ALIGN(size, align) : size; > > if (type == PRIMARY_INTERFACE) { > epc = epf->epc; > @@ -303,7 +312,7 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar, > } > > dev = epc->dev.parent; > - space = dma_alloc_coherent(dev, size, &phys_addr, GFP_KERNEL); > + space = dma_alloc_coherent(dev, aligned_size, &phys_addr, GFP_KERNEL); > if (!space) { > dev_err(dev, "failed to allocate mem space\n"); > return NULL; > > -- > 2.47.2 >
On Mon 07 Apr 2025 at 17:35, Niklas Cassel <cassel@kernel.org> wrote: > Hello Jerome, > > On Mon, Apr 07, 2025 at 04:39:08PM +0200, Jerome Brunet wrote: >> When trying to allocate space for an endpoint function on a BAR with a >> fixed size, the size saved in the 'struct pci_epf_bar' should be the fixed >> size. This is expected by pci_epc_set_bar(). >> >> However, if the fixed_size is smaller that the alignment, the size saved >> in the 'struct pci_epf_bar' matches the alignment and it is a problem for >> pci_epc_set_bar(). >> >> To solve this, continue to allocate space that match the iATU alignment >> requirement but save the size that matches what is present in the BAR. >> >> Fixes: 2a9a801620ef ("PCI: endpoint: Add support to specify alignment for buffers allocated to BARs") >> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com> >> --- >> drivers/pci/endpoint/pci-epf-core.c | 25 +++++++++++++++++-------- >> 1 file changed, 17 insertions(+), 8 deletions(-) >> >> diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c >> index b7deb0ee1760b23a24f49abf3baf53ea2f273476..fb902b751e1c965c902c5199d57969ae0a757c2e 100644 >> --- a/drivers/pci/endpoint/pci-epf-core.c >> +++ b/drivers/pci/endpoint/pci-epf-core.c >> @@ -225,6 +225,7 @@ void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar, >> struct device *dev; >> struct pci_epf_bar *epf_bar; >> struct pci_epc *epc; >> + size_t size; >> >> if (!addr) >> return; >> @@ -237,9 +238,12 @@ void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar, >> epf_bar = epf->sec_epc_bar; >> } >> >> + size = epf_bar[bar].size; >> + if (epc_features->align) >> + size = ALIGN(size, epc_features->align); > > Personally, I think that you should just save the aligned_size / mem_size / > backing_mem_size as a new struct member, as that avoids the risk that someone > later modifies pci_epf_alloc_space() but forgets to update > pci_epf_free_space() accordingly. I tried but it looked a bit silly to store that when it was only a matter of calling ALIGN() with parameters we already had, and it is supposed to be only used in those two functions. > > But I will leave the decision to the PCI endpoint maintainers. > Ultimately, I do not have a strong opinion on this. Either way is fine by me. > > Kind regards, > Niklas > > >> + >> dev = epc->dev.parent; >> - dma_free_coherent(dev, epf_bar[bar].size, addr, >> - epf_bar[bar].phys_addr); >> + dma_free_coherent(dev, size, addr, epf_bar[bar].phys_addr); >> >> epf_bar[bar].phys_addr = 0; >> epf_bar[bar].addr = NULL; >> @@ -266,7 +270,7 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar, >> enum pci_epc_interface_type type) >> { >> u64 bar_fixed_size = epc_features->bar[bar].fixed_size; >> - size_t align = epc_features->align; >> + size_t aligned_size, align = epc_features->align; >> struct pci_epf_bar *epf_bar; >> dma_addr_t phys_addr; >> struct pci_epc *epc; >> @@ -287,12 +291,17 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar, >> return NULL; >> } >> size = bar_fixed_size; >> + } else { >> + /* BAR size must be power of two */ >> + size = roundup_pow_of_two(size); >> } >> >> - if (align) >> - size = ALIGN(size, align); >> - else >> - size = roundup_pow_of_two(size); >> + /* >> + * Allocate enough memory to accommodate the iATU alignment requirement. >> + * In most cases, this will be the same as .size but it might be different >> + * if, for example, the fixed size of a BAR is smaller than align >> + */ >> + aligned_size = align ? ALIGN(size, align) : size; >> >> if (type == PRIMARY_INTERFACE) { >> epc = epf->epc; >> @@ -303,7 +312,7 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar, >> } >> >> dev = epc->dev.parent; >> - space = dma_alloc_coherent(dev, size, &phys_addr, GFP_KERNEL); >> + space = dma_alloc_coherent(dev, aligned_size, &phys_addr, GFP_KERNEL); >> if (!space) { >> dev_err(dev, "failed to allocate mem space\n"); >> return NULL; >> >> -- >> 2.47.2 >>
diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c index b7deb0ee1760b23a24f49abf3baf53ea2f273476..fb902b751e1c965c902c5199d57969ae0a757c2e 100644 --- a/drivers/pci/endpoint/pci-epf-core.c +++ b/drivers/pci/endpoint/pci-epf-core.c @@ -225,6 +225,7 @@ void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar, struct device *dev; struct pci_epf_bar *epf_bar; struct pci_epc *epc; + size_t size; if (!addr) return; @@ -237,9 +238,12 @@ void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar, epf_bar = epf->sec_epc_bar; } + size = epf_bar[bar].size; + if (epc_features->align) + size = ALIGN(size, epc_features->align); + dev = epc->dev.parent; - dma_free_coherent(dev, epf_bar[bar].size, addr, - epf_bar[bar].phys_addr); + dma_free_coherent(dev, size, addr, epf_bar[bar].phys_addr); epf_bar[bar].phys_addr = 0; epf_bar[bar].addr = NULL; @@ -266,7 +270,7 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar, enum pci_epc_interface_type type) { u64 bar_fixed_size = epc_features->bar[bar].fixed_size; - size_t align = epc_features->align; + size_t aligned_size, align = epc_features->align; struct pci_epf_bar *epf_bar; dma_addr_t phys_addr; struct pci_epc *epc; @@ -287,12 +291,17 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar, return NULL; } size = bar_fixed_size; + } else { + /* BAR size must be power of two */ + size = roundup_pow_of_two(size); } - if (align) - size = ALIGN(size, align); - else - size = roundup_pow_of_two(size); + /* + * Allocate enough memory to accommodate the iATU alignment requirement. + * In most cases, this will be the same as .size but it might be different + * if, for example, the fixed size of a BAR is smaller than align + */ + aligned_size = align ? ALIGN(size, align) : size; if (type == PRIMARY_INTERFACE) { epc = epf->epc; @@ -303,7 +312,7 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar, } dev = epc->dev.parent; - space = dma_alloc_coherent(dev, size, &phys_addr, GFP_KERNEL); + space = dma_alloc_coherent(dev, aligned_size, &phys_addr, GFP_KERNEL); if (!space) { dev_err(dev, "failed to allocate mem space\n"); return NULL;
When trying to allocate space for an endpoint function on a BAR with a fixed size, the size saved in the 'struct pci_epf_bar' should be the fixed size. This is expected by pci_epc_set_bar(). However, if the fixed_size is smaller that the alignment, the size saved in the 'struct pci_epf_bar' matches the alignment and it is a problem for pci_epc_set_bar(). To solve this, continue to allocate space that match the iATU alignment requirement but save the size that matches what is present in the BAR. Fixes: 2a9a801620ef ("PCI: endpoint: Add support to specify alignment for buffers allocated to BARs") Signed-off-by: Jerome Brunet <jbrunet@baylibre.com> --- drivers/pci/endpoint/pci-epf-core.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-)