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Date: Mon, 17 Jun 2019 15:08:59 +0300
From: Oded Gabbay <oded.gabbay@...il.com>
To: Tomer Tayar <ttayar@...ana.ai>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] habanalabs: Allow accessing host mapped addresses via debugfs
On Sun, Jun 16, 2019 at 4:48 PM Tomer Tayar <ttayar@...ana.ai> wrote:
>
> 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@...ana.ai>
> ---
> .../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@...il.com
> 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@...il.com
> 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
>
This patch is:
Reviewed-by: Oded Gabbay <oded.gabbay@...il.com>
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