Re: [PATCH v12 1/1] vfio/nvgpu: Add vfio pci variant module for grace hopper

[kernel test robot <lkp@intel.com>]

Hi,

kernel test robot noticed the following build warnings:

[auto build test WARNING on awilliam-vfio/for-linus]
[also build test WARNING on linus/master v6.6 next-20231103]
[cannot apply to awilliam-vfio/next]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/ankita-nvidia-com/vfio-nvgpu-Add-vfio-pci-variant-module-for-grace-hopper/20231017-131546
base:   https://github.com/awilliam/linux-vfio.git for-linus
patch link:    https://lore.kernel.org/r/20231015163047.20391-1-ankita%40nvidia.com
patch subject: [PATCH v12 1/1] vfio/nvgpu: Add vfio pci variant module for grace hopper
config: powerpc-allmodconfig (https://download.01.org/0day-ci/archive/20231104/202311041743.tL7StQAH-lkp@intel.com/config)
compiler: powerpc64-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231104/202311041743.tL7StQAH-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202311041743.tL7StQAH-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/vfio/pci/nvgrace-gpu/main.c:226:9: warning: no previous prototype for 'nvgrace_gpu_read_mem' [-Wmissing-prototypes]
     226 | ssize_t nvgrace_gpu_read_mem(void __user *buf, size_t count, loff_t *ppos,
         |         ^~~~~~~~~~~~~~~~~~~~
>> drivers/vfio/pci/nvgrace-gpu/main.c:298:9: warning: no previous prototype for 'nvgrace_gpu_write_mem' [-Wmissing-prototypes]
     298 | ssize_t nvgrace_gpu_write_mem(size_t count, loff_t *ppos, const void __user *buf,
         |         ^~~~~~~~~~~~~~~~~~~~~


vim +/nvgrace_gpu_read_mem +226 drivers/vfio/pci/nvgrace-gpu/main.c

   214	
   215	/*
   216	 * Read count bytes from the device memory at an offset. The actual device
   217	 * memory size (available) may not be a power-of-2. So the driver fakes
   218	 * the size to a power-of-2 (reported) when exposing to a user space driver.
   219	 *
   220	 * Read request beyond the actual device size is filled with ~0, while
   221	 * those beyond the actual reported size is skipped.
   222	 *
   223	 * A read from a negative or an offset greater than reported size, a negative
   224	 * count are considered error conditions and returned with an -EINVAL.
   225	 */
 > 226	ssize_t nvgrace_gpu_read_mem(void __user *buf, size_t count, loff_t *ppos,
   227				      struct nvgrace_gpu_vfio_pci_core_device *nvdev)
   228	{
   229		u64 offset = *ppos & VFIO_PCI_OFFSET_MASK;
   230		size_t mem_count, i, bar_size = roundup_pow_of_two(nvdev->memlength);
   231		u8 val = 0xFF;
   232	
   233		if (offset >= bar_size)
   234			return -EINVAL;
   235	
   236		/* Clip short the read request beyond reported BAR size */
   237		count = min(count, bar_size - (size_t)offset);
   238	
   239		/*
   240		 * Determine how many bytes to be actually read from the device memory.
   241		 * Read request beyond the actual device memory size is filled with ~0,
   242		 * while those beyond the actual reported size is skipped.
   243		 */
   244		if (offset >= nvdev->memlength)
   245			mem_count = 0;
   246		else
   247			mem_count = min(count, nvdev->memlength - (size_t)offset);
   248	
   249		/*
   250		 * Handle read on the BAR2 region. Map to the target device memory
   251		 * physical address and copy to the request read buffer.
   252		 */
   253		if (copy_to_user(buf, (u8 *)nvdev->memmap + offset, mem_count))
   254			return -EFAULT;
   255	
   256		/*
   257		 * Only the device memory present on the hardware is mapped, which may
   258		 * not be power-of-2 aligned. A read to an offset beyond the device memory
   259		 * size is filled with ~0.
   260		 */
   261		for (i = mem_count; i < count; i++)
   262			put_user(val, (unsigned char __user *)(buf + i));
   263	
   264		*ppos += count;
   265		return count;
   266	}
   267	
   268	static ssize_t nvgrace_gpu_vfio_pci_read(struct vfio_device *core_vdev,
   269						  char __user *buf, size_t count, loff_t *ppos)
   270	{
   271		unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
   272		struct nvgrace_gpu_vfio_pci_core_device *nvdev = container_of(
   273			core_vdev, struct nvgrace_gpu_vfio_pci_core_device, core_device.vdev);
   274		int ret;
   275	
   276		if (index == VFIO_PCI_BAR2_REGION_INDEX) {
   277			ret = nvgrace_gpu_memmap(nvdev);
   278			if (ret)
   279				return ret;
   280	
   281			return nvgrace_gpu_read_mem(buf, count, ppos, nvdev);
   282		}
   283	
   284		return vfio_pci_core_read(core_vdev, buf, count, ppos);
   285	}
   286	
   287	/*
   288	 * Write count bytes to the device memory at a given offset. The actual device
   289	 * memory size (available) may not be a power-of-2. So the driver fakes the
   290	 * size to a power-of-2 (reported) when exposing to a user space driver.
   291	 *
   292	 * Write request beyond the actual device size are dropped, while those
   293	 * beyond the actual reported size are skipped entirely.
   294	 *
   295	 * A write to a negative or an offset greater than the reported size, a
   296	 * negative count are considered error conditions and returned with an -EINVAL.
   297	 */
 > 298	ssize_t nvgrace_gpu_write_mem(size_t count, loff_t *ppos, const void __user *buf,
   299				       struct nvgrace_gpu_vfio_pci_core_device *nvdev)
   300	{
   301		u64 offset = *ppos & VFIO_PCI_OFFSET_MASK;
   302		size_t mem_count, bar_size = roundup_pow_of_two(nvdev->memlength);
   303	
   304		if (offset >= bar_size)
   305			return -EINVAL;
   306	
   307		/* Clip short the write request beyond reported BAR size */
   308		count = min(count, bar_size - (size_t)offset);
   309	
   310		/*
   311		 * Determine how many bytes to be actually written to the device memory.
   312		 * Do not write to the offset beyond available size.
   313		 */
   314		if (offset >= nvdev->memlength)
   315			goto exitfn;
   316	
   317		mem_count = min(count, nvdev->memlength - (size_t)offset);
   318	
   319		/*
   320		 * Only the device memory present on the hardware is mapped, which may
   321		 * not be power-of-2 aligned. A write to the BAR2 region implies an
   322		 * access outside the available device memory on the hardware. Drop
   323		 * those write requests.
   324		 */
   325		if (copy_from_user((u8 *)nvdev->memmap + offset, buf, mem_count))
   326			return -EFAULT;
   327	
   328	exitfn:
   329		*ppos += count;
   330		return count;
   331	}
   332	

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