powerpc/powernv: Override dma_get_required_mask()
The dma_get_required_mask() function is used by some drivers to
query the platform about what DMA mask is needed to cover all of
memory. This is a bit of a strange semantic when we have to choose
between IOMMU translation or bypass, but essentially what it means
is "what DMA mask will give best performances".
Currently, our IOMMU backend always returns a 32-bit mask here, we
don't do anything special to it when we have bypass available. This
causes some drivers to choose a 32-bit mask, thus losing the ability
to use the bypass window, thinking this is more efficient. The problem
was reported from the driver of following device:
0004:03:00.0 0107: 1000:0087 (rev 05)
0004:03:00.0 Serial Attached SCSI controller: LSI Logic / Symbios \
Logic SAS2308 PCI-Express Fusion-MPT SAS-2 (rev 05)
This patch adds an override of that function in order to, instead,
return a 64-bit mask whenever a bypass window is available in order
for drivers to prefer this configuration.
Reported-by: Murali N. Iyer <mniyer@us.ibm.com>
Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 8685dac..0fd6bdb 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -889,6 +889,28 @@
return 0;
}
+static u64 pnv_pci_ioda_dma_get_required_mask(struct pnv_phb *phb,
+ struct pci_dev *pdev)
+{
+ struct pci_dn *pdn = pci_get_pdn(pdev);
+ struct pnv_ioda_pe *pe;
+ u64 end, mask;
+
+ if (WARN_ON(!pdn || pdn->pe_number == IODA_INVALID_PE))
+ return 0;
+
+ pe = &phb->ioda.pe_array[pdn->pe_number];
+ if (!pe->tce_bypass_enabled)
+ return __dma_get_required_mask(&pdev->dev);
+
+
+ end = pe->tce_bypass_base + memblock_end_of_DRAM();
+ mask = 1ULL << (fls64(end) - 1);
+ mask += mask - 1;
+
+ return mask;
+}
+
static void pnv_ioda_setup_bus_dma(struct pnv_ioda_pe *pe,
struct pci_bus *bus,
bool add_to_iommu_group)
@@ -1781,6 +1803,7 @@
/* Setup TCEs */
phb->dma_dev_setup = pnv_pci_ioda_dma_dev_setup;
phb->dma_set_mask = pnv_pci_ioda_dma_set_mask;
+ phb->dma_get_required_mask = pnv_pci_ioda_dma_get_required_mask;
/* Setup shutdown function for kexec */
phb->shutdown = pnv_pci_ioda_shutdown;
diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
index b854b57..e9f509b 100644
--- a/arch/powerpc/platforms/powernv/pci.c
+++ b/arch/powerpc/platforms/powernv/pci.c
@@ -761,6 +761,17 @@
return __dma_set_mask(&pdev->dev, dma_mask);
}
+u64 pnv_pci_dma_get_required_mask(struct pci_dev *pdev)
+{
+ struct pci_controller *hose = pci_bus_to_host(pdev->bus);
+ struct pnv_phb *phb = hose->private_data;
+
+ if (phb && phb->dma_get_required_mask)
+ return phb->dma_get_required_mask(phb, pdev);
+
+ return __dma_get_required_mask(&pdev->dev);
+}
+
void pnv_pci_shutdown(void)
{
struct pci_controller *hose;
diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
index 27594cf..34d29eb 100644
--- a/arch/powerpc/platforms/powernv/pci.h
+++ b/arch/powerpc/platforms/powernv/pci.h
@@ -124,6 +124,8 @@
void (*dma_dev_setup)(struct pnv_phb *phb, struct pci_dev *pdev);
int (*dma_set_mask)(struct pnv_phb *phb, struct pci_dev *pdev,
u64 dma_mask);
+ u64 (*dma_get_required_mask)(struct pnv_phb *phb,
+ struct pci_dev *pdev);
void (*fixup_phb)(struct pci_controller *hose);
u32 (*bdfn_to_pe)(struct pnv_phb *phb, struct pci_bus *bus, u32 devfn);
void (*shutdown)(struct pnv_phb *phb);
diff --git a/arch/powerpc/platforms/powernv/powernv.h b/arch/powerpc/platforms/powernv/powernv.h
index 75501bf..6c8e2d1 100644
--- a/arch/powerpc/platforms/powernv/powernv.h
+++ b/arch/powerpc/platforms/powernv/powernv.h
@@ -13,6 +13,7 @@
extern void pnv_pci_init(void);
extern void pnv_pci_shutdown(void);
extern int pnv_pci_dma_set_mask(struct pci_dev *pdev, u64 dma_mask);
+extern u64 pnv_pci_dma_get_required_mask(struct pci_dev *pdev);
#else
static inline void pnv_pci_init(void) { }
static inline void pnv_pci_shutdown(void) { }
@@ -21,6 +22,11 @@
{
return -ENODEV;
}
+
+static inline u64 pnv_pci_dma_get_required_mask(struct pci_dev *pdev)
+{
+ return 0;
+}
#endif
extern void pnv_lpc_init(void);
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index bb1fc9b..3f9546d 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -173,6 +173,14 @@
return __dma_set_mask(dev, dma_mask);
}
+static u64 pnv_dma_get_required_mask(struct device *dev)
+{
+ if (dev_is_pci(dev))
+ return pnv_pci_dma_get_required_mask(to_pci_dev(dev));
+
+ return __dma_get_required_mask(dev);
+}
+
static void pnv_shutdown(void)
{
/* Let the PCI code clear up IODA tables */
@@ -335,6 +343,7 @@
.power_save = power7_idle,
.calibrate_decr = generic_calibrate_decr,
.dma_set_mask = pnv_dma_set_mask,
+ .dma_get_required_mask = pnv_dma_get_required_mask,
#ifdef CONFIG_KEXEC
.kexec_cpu_down = pnv_kexec_cpu_down,
#endif