[PATCH] habanalabs: Allow accessing host mapped addresses via debugfs

From: Tomer Tayar
Date: Sun Jun 16 2019 - 09:53:32 EST

Allows using the addr/data32 debugfs nodes to access a device VA of a
host mapped memory when the IOMMU is disabled.

Due to the possible large amount of a user host mapped memory, the
driver doesn't maintain a database with the host addresses per device VA.
When the IOMMU is disabled, this missing info is being overcome by
simply using phys_to_virt(). However, this is not useful when the IOMMU
is enabled, and thus the enforced limitation.

Signed-off-by: Tomer Tayar <ttayar@xxxxxxxxx>
---
.../ABI/testing/debugfs-driver-habanalabs | 11 ++++--
drivers/misc/habanalabs/debugfs.c | 35 ++++++++++++-------
drivers/misc/habanalabs/goya/goya.c | 19 +++++++---
3 files changed, 46 insertions(+), 19 deletions(-)

diff --git a/Documentation/ABI/testing/debugfs-driver-habanalabs b/Documentation/ABI/testing/debugfs-driver-habanalabs
index 2f5b80be07a3..18191c2becab 100644
--- a/Documentation/ABI/testing/debugfs-driver-habanalabs
+++ b/Documentation/ABI/testing/debugfs-driver-habanalabs
@@ -3,7 +3,10 @@ Date: Jan 2019
KernelVersion: 5.1
Contact: oded.gabbay@xxxxxxxxx
Description: Sets the device address to be used for read or write through
- PCI bar. The acceptable value is a string that starts with "0x"
+ PCI bar, or the device VA of a host mapped memory to be read or
+ written directly from the host. The latter option is allowed
+ only when the IOMMU is disabled.
+ The acceptable value is a string that starts with "0x"

What: /sys/kernel/debug/habanalabs/hl<n>/command_buffers
Date: Jan 2019
@@ -33,10 +36,12 @@ Contact: oded.gabbay@xxxxxxxxx
Description: Allows the root user to read or write directly through the
device's PCI bar. Writing to this file generates a write
transaction while reading from the file generates a read
- transcation. This custom interface is needed (instead of using
+ transaction. This custom interface is needed (instead of using
the generic Linux user-space PCI mapping) because the DDR bar
is very small compared to the DDR memory and only the driver can
- move the bar before and after the transaction
+ move the bar before and after the transaction.
+ If the IOMMU is disabled, it also allows the root user to read
+ or write from the host a device VA of a host mapped memory

What: /sys/kernel/debug/habanalabs/hl<n>/device
Date: Jan 2019
diff --git a/drivers/misc/habanalabs/debugfs.c b/drivers/misc/habanalabs/debugfs.c
index 886f8ea82499..17974919b760 100644
--- a/drivers/misc/habanalabs/debugfs.c
+++ b/drivers/misc/habanalabs/debugfs.c
@@ -500,6 +500,25 @@ static ssize_t mmu_write(struct file *file, const char __user *buf,
return -EINVAL;
}

+static bool hl_is_device_va(struct hl_device *hdev, u64 addr)
+{
+ struct asic_fixed_properties *prop = &hdev->asic_prop;
+
+ if (!hdev->mmu_enable)
+ goto out;
+
+ if (hdev->dram_supports_virtual_memory &&
+ addr >= prop->va_space_dram_start_address &&
+ addr < prop->va_space_dram_end_address)
+ return true;
+
+ if (addr >= prop->va_space_host_start_address &&
+ addr < prop->va_space_host_end_address)
+ return true;
+out:
+ return false;
+}
+
static int device_va_to_pa(struct hl_device *hdev, u64 virt_addr,
u64 *phys_addr)
{
@@ -573,7 +592,6 @@ static ssize_t hl_data_read32(struct file *f, char __user *buf,
{
struct hl_dbg_device_entry *entry = file_inode(f)->i_private;
struct hl_device *hdev = entry->hdev;
- struct asic_fixed_properties *prop = &hdev->asic_prop;
char tmp_buf[32];
u64 addr = entry->addr;
u32 val;
@@ -582,11 +600,8 @@ static ssize_t hl_data_read32(struct file *f, char __user *buf,
if (*ppos)
return 0;

- if (addr >= prop->va_space_dram_start_address &&
- addr < prop->va_space_dram_end_address &&
- hdev->mmu_enable &&
- hdev->dram_supports_virtual_memory) {
- rc = device_va_to_pa(hdev, entry->addr, &addr);
+ if (hl_is_device_va(hdev, addr)) {
+ rc = device_va_to_pa(hdev, addr, &addr);
if (rc)
return rc;
}
@@ -607,7 +622,6 @@ static ssize_t hl_data_write32(struct file *f, const char __user *buf,
{
struct hl_dbg_device_entry *entry = file_inode(f)->i_private;
struct hl_device *hdev = entry->hdev;
- struct asic_fixed_properties *prop = &hdev->asic_prop;
u64 addr = entry->addr;
u32 value;
ssize_t rc;
@@ -616,11 +630,8 @@ static ssize_t hl_data_write32(struct file *f, const char __user *buf,
if (rc)
return rc;

- if (addr >= prop->va_space_dram_start_address &&
- addr < prop->va_space_dram_end_address &&
- hdev->mmu_enable &&
- hdev->dram_supports_virtual_memory) {
- rc = device_va_to_pa(hdev, entry->addr, &addr);
+ if (hl_is_device_va(hdev, addr)) {
+ rc = device_va_to_pa(hdev, addr, &addr);
if (rc)
return rc;
}
diff --git a/drivers/misc/habanalabs/goya/goya.c b/drivers/misc/habanalabs/goya/goya.c
index e8b3a31d211f..ce127a6f606f 100644
--- a/drivers/misc/habanalabs/goya/goya.c
+++ b/drivers/misc/habanalabs/goya/goya.c
@@ -14,6 +14,7 @@
#include <linux/genalloc.h>
#include <linux/hwmon.h>
#include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/iommu.h>

/*
* GOYA security scheme:
@@ -3941,10 +3942,11 @@ static void goya_clear_sm_regs(struct hl_device *hdev)
}

/*
- * goya_debugfs_read32 - read a 32bit value from a given device address
+ * goya_debugfs_read32 - read a 32bit value from a given device or a host mapped
+ * address.
*
* @hdev: pointer to hl_device structure
- * @addr: address in device
+ * @addr: device or host mapped address
* @val: returned value
*
* In case of DDR address that is not mapped into the default aperture that
@@ -3985,6 +3987,10 @@ static int goya_debugfs_read32(struct hl_device *hdev, u64 addr, u32 *val)
}
if (ddr_bar_addr == U64_MAX)
rc = -EIO;
+
+ } else if (addr >= HOST_PHYS_BASE && !iommu_present(&pci_bus_type)) {
+ *val = *(u32 *) phys_to_virt(addr - HOST_PHYS_BASE);
+
} else {
rc = -EFAULT;
}
@@ -3993,10 +3999,11 @@ static int goya_debugfs_read32(struct hl_device *hdev, u64 addr, u32 *val)
}

/*
- * goya_debugfs_write32 - write a 32bit value to a given device address
+ * goya_debugfs_write32 - write a 32bit value to a given device or a host mapped
+ * address.
*
* @hdev: pointer to hl_device structure
- * @addr: address in device
+ * @addr: device or host mapped address
* @val: returned value
*
* In case of DDR address that is not mapped into the default aperture that
@@ -4037,6 +4044,10 @@ static int goya_debugfs_write32(struct hl_device *hdev, u64 addr, u32 val)
}
if (ddr_bar_addr == U64_MAX)
rc = -EIO;
+
+ } else if (addr >= HOST_PHYS_BASE && !iommu_present(&pci_bus_type)) {
+ *(u32 *) phys_to_virt(addr - HOST_PHYS_BASE) = val;
+
} else {
rc = -EFAULT;
}
--
2.17.1