Intel ID: PSIRT-TA-201910-001 CVEID: CVE-2019-14615
Summary of Vulnerability ------------------------ Insufficient control flow in certain data structures for some Intel(R) Processors with Intel Processor Graphics may allow an unauthenticated user to potentially enable information disclosure via local access
Products affected: ------------------ Intel CPU’s with Gen7, Gen7.5 and Gen9 Graphics.
Mitigation Summary ------------------ This patch provides mitigation for Gen7 and Gen7.5 hardware only. Patch for Gen9 devices have been provided and merged to Linux mainline, and backported to stable kernels. Note that Gen8 is not impacted due to a previously implemented workaround.
The mitigation involves submitting a custom EU kernel prior to every context restore, in order to forcibly clear down residual EU and URB resources.
This security mitigation change does not trigger any known performance regression. Performance is on par with current mainline/drm-tip.
Note on Address Space Isolation (Full PPGTT) --------------------------------------------
Isolation of EU kernel assets should be considered complementary to the existing support for address space isolation (aka Full PPGTT), since without address space isolation there is minimal value in preventing leakage between EU contexts. Full PPGTT has long been supported on Gen Gfx devices since Gen8, and protection against EU residual leakage is a welcome addition for these newer platforms.
By contrast, Gen7 and Gen7.5 device introduced Full PPGTT support only as a hardware development feature for anticipated Gen8 productization. Support was never intended for, or provided to the Linux kernels for these platforms. Recent work (still ongoing) to the mainline kernel is retroactively providing this support, but due to the level of complexity it is not practical to attempt to backport this to earlier stable kernels. Since without Full PPGTT, EU residuals protection has questionable benefit, *there are no plans to provide stable kernel backports for this patch series.*
Mika Kuoppala (1): drm/i915: Add mechanism to submit a context WA on ring submission
Prathap Kumar Valsan (1): drm/i915/gen7: Clear all EU/L3 residual contexts
drivers/gpu/drm/i915/Makefile | 1 + drivers/gpu/drm/i915/gt/gen7_renderclear.c | 535 ++++++++++++++++++ drivers/gpu/drm/i915/gt/gen7_renderclear.h | 15 + drivers/gpu/drm/i915/gt/intel_gpu_commands.h | 17 +- .../gpu/drm/i915/gt/intel_ring_submission.c | 133 ++++- drivers/gpu/drm/i915/i915_utils.h | 5 + 6 files changed, 700 insertions(+), 6 deletions(-) create mode 100644 drivers/gpu/drm/i915/gt/gen7_renderclear.c create mode 100644 drivers/gpu/drm/i915/gt/gen7_renderclear.h