Commit cd15b048 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt
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powerpc/powernv: Add iommu DMA bypass support for IODA2



This patch adds the support for to create a direct iommu "bypass"
window on IODA2 bridges (such as Power8) allowing to bypass iommu
page translation completely for 64-bit DMA capable devices, thus
significantly improving DMA performances.

Additionally, this adds a hook to the struct iommu_table so that
the IOMMU API / VFIO can disable the bypass when external ownership
is requested, since in that case, the device will be used by an
environment such as userspace or a KVM guest which must not be
allowed to bypass translations.
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent ea961a82
......@@ -134,6 +134,7 @@ static inline int dma_supported(struct device *dev, u64 mask)
}
extern int dma_set_mask(struct device *dev, u64 dma_mask);
extern int __dma_set_mask(struct device *dev, u64 dma_mask);
#define dma_alloc_coherent(d,s,h,f) dma_alloc_attrs(d,s,h,f,NULL)
......
......@@ -77,6 +77,7 @@ struct iommu_table {
#ifdef CONFIG_IOMMU_API
struct iommu_group *it_group;
#endif
void (*set_bypass)(struct iommu_table *tbl, bool enable);
};
/* Pure 2^n version of get_order */
......
......@@ -191,12 +191,10 @@ EXPORT_SYMBOL(dma_direct_ops);
#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
int dma_set_mask(struct device *dev, u64 dma_mask)
int __dma_set_mask(struct device *dev, u64 dma_mask)
{
struct dma_map_ops *dma_ops = get_dma_ops(dev);
if (ppc_md.dma_set_mask)
return ppc_md.dma_set_mask(dev, dma_mask);
if ((dma_ops != NULL) && (dma_ops->set_dma_mask != NULL))
return dma_ops->set_dma_mask(dev, dma_mask);
if (!dev->dma_mask || !dma_supported(dev, dma_mask))
......@@ -204,6 +202,12 @@ int dma_set_mask(struct device *dev, u64 dma_mask)
*dev->dma_mask = dma_mask;
return 0;
}
int dma_set_mask(struct device *dev, u64 dma_mask)
{
if (ppc_md.dma_set_mask)
return ppc_md.dma_set_mask(dev, dma_mask);
return __dma_set_mask(dev, dma_mask);
}
EXPORT_SYMBOL(dma_set_mask);
u64 dma_get_required_mask(struct device *dev)
......
......@@ -1088,6 +1088,14 @@ int iommu_take_ownership(struct iommu_table *tbl)
memset(tbl->it_map, 0xff, sz);
iommu_clear_tces_and_put_pages(tbl, tbl->it_offset, tbl->it_size);
/*
* Disable iommu bypass, otherwise the user can DMA to all of
* our physical memory via the bypass window instead of just
* the pages that has been explicitly mapped into the iommu
*/
if (tbl->set_bypass)
tbl->set_bypass(tbl, false);
return 0;
}
EXPORT_SYMBOL_GPL(iommu_take_ownership);
......@@ -1102,6 +1110,10 @@ void iommu_release_ownership(struct iommu_table *tbl)
/* Restore bit#0 set by iommu_init_table() */
if (tbl->it_offset == 0)
set_bit(0, tbl->it_map);
/* The kernel owns the device now, we can restore the iommu bypass */
if (tbl->set_bypass)
tbl->set_bypass(tbl, true);
}
EXPORT_SYMBOL_GPL(iommu_release_ownership);
......
......@@ -21,6 +21,7 @@
#include <linux/irq.h>
#include <linux/io.h>
#include <linux/msi.h>
#include <linux/memblock.h>
#include <asm/sections.h>
#include <asm/io.h>
......@@ -460,9 +461,39 @@ static void pnv_pci_ioda_dma_dev_setup(struct pnv_phb *phb, struct pci_dev *pdev
return;
pe = &phb->ioda.pe_array[pdn->pe_number];
WARN_ON(get_dma_ops(&pdev->dev) != &dma_iommu_ops);
set_iommu_table_base_and_group(&pdev->dev, &pe->tce32_table);
}
static int pnv_pci_ioda_dma_set_mask(struct pnv_phb *phb,
struct pci_dev *pdev, u64 dma_mask)
{
struct pci_dn *pdn = pci_get_pdn(pdev);
struct pnv_ioda_pe *pe;
uint64_t top;
bool bypass = false;
if (WARN_ON(!pdn || pdn->pe_number == IODA_INVALID_PE))
return -ENODEV;;
pe = &phb->ioda.pe_array[pdn->pe_number];
if (pe->tce_bypass_enabled) {
top = pe->tce_bypass_base + memblock_end_of_DRAM() - 1;
bypass = (dma_mask >= top);
}
if (bypass) {
dev_info(&pdev->dev, "Using 64-bit DMA iommu bypass\n");
set_dma_ops(&pdev->dev, &dma_direct_ops);
set_dma_offset(&pdev->dev, pe->tce_bypass_base);
} else {
dev_info(&pdev->dev, "Using 32-bit DMA via iommu\n");
set_dma_ops(&pdev->dev, &dma_iommu_ops);
set_iommu_table_base(&pdev->dev, &pe->tce32_table);
}
return 0;
}
static void pnv_ioda_setup_bus_dma(struct pnv_ioda_pe *pe, struct pci_bus *bus)
{
struct pci_dev *dev;
......@@ -657,6 +688,56 @@ static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb,
__free_pages(tce_mem, get_order(TCE32_TABLE_SIZE * segs));
}
static void pnv_pci_ioda2_set_bypass(struct iommu_table *tbl, bool enable)
{
struct pnv_ioda_pe *pe = container_of(tbl, struct pnv_ioda_pe,
tce32_table);
uint16_t window_id = (pe->pe_number << 1 ) + 1;
int64_t rc;
pe_info(pe, "%sabling 64-bit DMA bypass\n", enable ? "En" : "Dis");
if (enable) {
phys_addr_t top = memblock_end_of_DRAM();
top = roundup_pow_of_two(top);
rc = opal_pci_map_pe_dma_window_real(pe->phb->opal_id,
pe->pe_number,
window_id,
pe->tce_bypass_base,
top);
} else {
rc = opal_pci_map_pe_dma_window_real(pe->phb->opal_id,
pe->pe_number,
window_id,
pe->tce_bypass_base,
0);
/*
* We might want to reset the DMA ops of all devices on
* this PE. However in theory, that shouldn't be necessary
* as this is used for VFIO/KVM pass-through and the device
* hasn't yet been returned to its kernel driver
*/
}
if (rc)
pe_err(pe, "OPAL error %lld configuring bypass window\n", rc);
else
pe->tce_bypass_enabled = enable;
}
static void pnv_pci_ioda2_setup_bypass_pe(struct pnv_phb *phb,
struct pnv_ioda_pe *pe)
{
/* TVE #1 is selected by PCI address bit 59 */
pe->tce_bypass_base = 1ull << 59;
/* Install set_bypass callback for VFIO */
pe->tce32_table.set_bypass = pnv_pci_ioda2_set_bypass;
/* Enable bypass by default */
pnv_pci_ioda2_set_bypass(&pe->tce32_table, true);
}
static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
struct pnv_ioda_pe *pe)
{
......@@ -727,6 +808,8 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
else
pnv_ioda_setup_bus_dma(pe, pe->pbus);
/* Also create a bypass window */
pnv_pci_ioda2_setup_bypass_pe(phb, pe);
return;
fail:
if (pe->tce32_seg >= 0)
......@@ -1286,6 +1369,7 @@ void __init pnv_pci_init_ioda_phb(struct device_node *np,
/* Setup TCEs */
phb->dma_dev_setup = pnv_pci_ioda_dma_dev_setup;
phb->dma_set_mask = pnv_pci_ioda_dma_set_mask;
/* Setup shutdown function for kexec */
phb->shutdown = pnv_pci_ioda_shutdown;
......
......@@ -634,6 +634,16 @@ static void pnv_pci_dma_dev_setup(struct pci_dev *pdev)
pnv_pci_dma_fallback_setup(hose, pdev);
}
int pnv_pci_dma_set_mask(struct pci_dev *pdev, u64 dma_mask)
{
struct pci_controller *hose = pci_bus_to_host(pdev->bus);
struct pnv_phb *phb = hose->private_data;
if (phb && phb->dma_set_mask)
return phb->dma_set_mask(phb, pdev, dma_mask);
return __dma_set_mask(&pdev->dev, dma_mask);
}
void pnv_pci_shutdown(void)
{
struct pci_controller *hose;
......
......@@ -54,7 +54,9 @@ struct pnv_ioda_pe {
struct iommu_table tce32_table;
phys_addr_t tce_inval_reg_phys;
/* XXX TODO: Add support for additional 64-bit iommus */
/* 64-bit TCE bypass region */
bool tce_bypass_enabled;
uint64_t tce_bypass_base;
/* MSIs. MVE index is identical for for 32 and 64 bit MSI
* and -1 if not supported. (It's actually identical to the
......@@ -113,6 +115,8 @@ struct pnv_phb {
unsigned int hwirq, unsigned int virq,
unsigned int is_64, struct msi_msg *msg);
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);
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);
......
......@@ -7,12 +7,20 @@ extern void pnv_smp_init(void);
static inline void pnv_smp_init(void) { }
#endif
struct pci_dev;
#ifdef CONFIG_PCI
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);
#else
static inline void pnv_pci_init(void) { }
static inline void pnv_pci_shutdown(void) { }
static inline int pnv_pci_dma_set_mask(struct pci_dev *pdev, u64 dma_mask)
{
return -ENODEV;
}
#endif
extern void pnv_lpc_init(void);
......
......@@ -27,6 +27,7 @@
#include <linux/interrupt.h>
#include <linux/bug.h>
#include <linux/cpuidle.h>
#include <linux/pci.h>
#include <asm/machdep.h>
#include <asm/firmware.h>
......@@ -141,6 +142,13 @@ static void pnv_progress(char *s, unsigned short hex)
{
}
static int pnv_dma_set_mask(struct device *dev, u64 dma_mask)
{
if (dev_is_pci(dev))
return pnv_pci_dma_set_mask(to_pci_dev(dev), dma_mask);
return __dma_set_mask(dev, dma_mask);
}
static void pnv_shutdown(void)
{
/* Let the PCI code clear up IODA tables */
......@@ -238,6 +246,7 @@ define_machine(powernv) {
.machine_shutdown = pnv_shutdown,
.power_save = powernv_idle,
.calibrate_decr = generic_calibrate_decr,
.dma_set_mask = pnv_dma_set_mask,
#ifdef CONFIG_KEXEC
.kexec_cpu_down = pnv_kexec_cpu_down,
#endif
......
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