The clear-residuals mitigate is a relatively heavy hammer and under some circumstances the user may wish to forgo the context isolation in order to meet some performance requirement. Introduce a generic module parameter to allow selectively enabling/disabling different mitigations.
Fixes: 47f8253d2b89 ("drm/i915/gen7: Clear all EU/L3 residual contexts") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: Jon Bloomfield jon.bloomfield@intel.com Cc: Rodrigo Vivi rodrigo.vivi@intel.com Cc: stable@vger.kernel.org # v5.7 --- drivers/gpu/drm/i915/Makefile | 1 + .../gpu/drm/i915/gt/intel_ring_submission.c | 4 +- drivers/gpu/drm/i915/i915_mitigations.c | 119 ++++++++++++++++++ drivers/gpu/drm/i915/i915_mitigations.h | 13 ++ 4 files changed, 136 insertions(+), 1 deletion(-) create mode 100644 drivers/gpu/drm/i915/i915_mitigations.c create mode 100644 drivers/gpu/drm/i915/i915_mitigations.h
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile index 4074d8cb0d6e..48f82c354611 100644 --- a/drivers/gpu/drm/i915/Makefile +++ b/drivers/gpu/drm/i915/Makefile @@ -38,6 +38,7 @@ i915-y += i915_drv.o \ i915_config.o \ i915_irq.o \ i915_getparam.o \ + i915_mitigations.o \ i915_params.o \ i915_pci.o \ i915_scatterlist.o \ diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c index 72d4722441bf..d529608d4456 100644 --- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c +++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c @@ -32,6 +32,7 @@ #include "gen6_ppgtt.h" #include "gen7_renderclear.h" #include "i915_drv.h" +#include "i915_mitigations.h" #include "intel_breadcrumbs.h" #include "intel_context.h" #include "intel_gt.h" @@ -920,7 +921,8 @@ static int switch_context(struct i915_request *rq) GEM_BUG_ON(HAS_EXECLISTS(engine->i915));
if (engine->wa_ctx.vma && ce != engine->kernel_context) { - if (engine->wa_ctx.vma->private != ce) { + if (engine->wa_ctx.vma->private != ce && + i915_mitigate_clear_residuals()) { ret = clear_residuals(rq); if (ret) return ret; diff --git a/drivers/gpu/drm/i915/i915_mitigations.c b/drivers/gpu/drm/i915/i915_mitigations.c new file mode 100644 index 000000000000..01ad74721e65 --- /dev/null +++ b/drivers/gpu/drm/i915/i915_mitigations.c @@ -0,0 +1,119 @@ +// SPDX-License-Identifier: MIT +/* + * Copyright © 2021 Intel Corporation + */ + +#include <linux/kernel.h> +#include <linux/moduleparam.h> +#include <linux/slab.h> +#include <linux/string.h> + +#include "i915_mitigations.h" + +static unsigned long mitigations = ~0UL; + +enum { + CLEAR_RESIDUALS = 0, +}; + +bool i915_mitigate_clear_residuals(void) +{ + return READ_ONCE(mitigations) & BIT(CLEAR_RESIDUALS); +} + +static int mitigations_parse(const char *arg) +{ + unsigned long new = ~0UL; + char *str, *sep, *tok; + bool first = true; + int err = 0; + + str = kstrdup(arg, GFP_KERNEL); + if (!str) + return -ENOMEM; + + for (sep = strim(str); (tok = strsep(&sep, ","));) { + bool enable = true; + + if (first) { + first = false; + + if (!strcmp(tok, "auto")) { + new = ~0UL; + continue; + } + + new = 0; + if (!strcmp(tok, "off")) + continue; + } + + if (*tok == '!') { + enable = !enable; + tok++; + } + + if (!strncmp(tok, "no", 2)) { + enable = !enable; + tok += 2; + } + + if (*tok == '\0') + continue; + + if (!strcmp(tok, "residuals")) { + if (enable) + new |= BIT(CLEAR_RESIDUALS); + else + new &= ~BIT(CLEAR_RESIDUALS); + } else { + err = -EINVAL; + break; + } + } + kfree(str); + if (err) + return err; + + WRITE_ONCE(mitigations, new); + return 0; +} + +static int mitigations_set(const char *val, const struct kernel_param *kp) +{ + int err; + + err = mitigations_parse(val); + if (err) + return err; + + err = param_set_charp(val, kp); + if (err) + return err; + + return 0; +} + +static const struct kernel_param_ops ops = { + .set = mitigations_set, + .get = param_get_charp, + .free = param_free_charp +}; + +static char *param; +module_param_cb_unsafe(mitigations, &ops, ¶m, 0600); +MODULE_PARM_DESC(mitigations, +"Selectively enable security mitigations for all Intel® GPUs.\n" +"\n" +" auto -- enables all mitigations required for the platform [default]\n" +" off -- disables all mitigations\n" +"\n" +"Individual mitigations can be enabled by passing a comma-separated string,\n" +"e.g. mitigations=residuals to enable only clearing residuals or\n" +"mitigations=auto,noresiduals to disable only the clear residual mitigation.\n" +"Either '!' or 'no' may be used to switch from enabling the mitigation to\n" +"disabling it.\n" +"\n" +"Active mitigations for Ivybridge, Baytrail, Haswell:\n" +" residuals -- clear all thread-local registers between contexts" +); diff --git a/drivers/gpu/drm/i915/i915_mitigations.h b/drivers/gpu/drm/i915/i915_mitigations.h new file mode 100644 index 000000000000..1359d8135287 --- /dev/null +++ b/drivers/gpu/drm/i915/i915_mitigations.h @@ -0,0 +1,13 @@ +/* SPDX-License-Identifier: MIT */ +/* + * Copyright © 2021 Intel Corporation + */ + +#ifndef __I915_MITIGATIONS_H__ +#define __I915_MITIGATIONS_H__ + +#include <linux/types.h> + +bool i915_mitigate_clear_residuals(void); + +#endif /* __I915_MITIGATIONS_H__ */