Commit 9f201aba authored Apr 06, 2019 by Oded Gabbay

habanalabs: prevent device PTE read/write during hard-reset



During hard-reset, contexts are closed as part of the tear-down process.
After a context is closed, the driver cleans up the page tables of that
context in the device's DRAM. This action is both dangerous and
unnecessary.

It is unnecessary, because the device is going through a hard-reset, which
means the device's DRAM contents are no longer valid and the device's MMU
is being reset.

It is dangerous, because if the hard-reset came as a result of a PCI
freeze, this action may cause the entire host machine to hang.

Therefore, prevent all device PTE updates when a hard-reset operation is
pending.

Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

parent 3f5398cf

drivers/misc/habanalabs/goya/goya.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -4058,6 +4058,9 @@ static u64 goya_read_pte(struct hl_device *hdev, u64 addr)
		{
		struct goya_device *goya = hdev->asic_specific;

		if (hdev->hard_reset_pending)
		return U64_MAX;

		return readq(hdev->pcie_bar[DDR_BAR_ID] +
		(addr - goya->ddr_bar_cur_addr));
		}
		@@ -4066,6 +4069,9 @@ static void goya_write_pte(struct hl_device *hdev, u64 addr, u64 val)
		{
		struct goya_device *goya = hdev->asic_specific;

		if (hdev->hard_reset_pending)
		return;

		writeq(val, hdev->pcie_bar[DDR_BAR_ID] +
		(addr - goya->ddr_bar_cur_addr));
		}