Verify that one context running on engine A cannot manipulate another
client's context concurrently running on engine B using unprivileged
access.

Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gt/selftest_lrc.c | 275 +++++++++++++++++++++----
 1 file changed, 238 insertions(+), 37 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/selftest_lrc.c 
b/drivers/gpu/drm/i915/gt/selftest_lrc.c
index 0524232378e4..e97adf1b7729 100644
--- a/drivers/gpu/drm/i915/gt/selftest_lrc.c
+++ b/drivers/gpu/drm/i915/gt/selftest_lrc.c
@@ -911,6 +911,7 @@ create_user_vma(struct i915_address_space *vm, unsigned 
long size)
 
 static struct i915_vma *
 store_context(struct intel_context *ce,
+             struct intel_engine_cs *engine,
              struct i915_vma *scratch,
              bool relative)
 {
@@ -928,7 +929,7 @@ store_context(struct intel_context *ce,
                return ERR_CAST(cs);
        }
 
-       defaults = shmem_pin_map(ce->engine->default_state);
+       defaults = shmem_pin_map(engine->default_state);
        if (!defaults) {
                i915_gem_object_unpin_map(batch->obj);
                i915_vma_put(batch);
@@ -960,7 +961,7 @@ store_context(struct intel_context *ce,
                        if (relative)
                                cmd |= MI_LRI_LRM_CS_MMIO;
                        else
-                               offset = ce->engine->mmio_base;
+                               offset = engine->mmio_base;
                }
 
                dw++;
@@ -979,7 +980,7 @@ store_context(struct intel_context *ce,
 
        *cs++ = MI_BATCH_BUFFER_END;
 
-       shmem_unpin_map(ce->engine->default_state, defaults);
+       shmem_unpin_map(engine->default_state, defaults);
 
        i915_gem_object_flush_map(batch->obj);
        i915_gem_object_unpin_map(batch->obj);
@@ -1002,23 +1003,48 @@ static int move_to_active(struct i915_request *rq,
        return err;
 }
 
+struct hwsp_semaphore {
+       u32 ggtt;
+       u32 *va;
+};
+
+static struct hwsp_semaphore hwsp_semaphore(struct intel_engine_cs *engine)
+{
+       struct hwsp_semaphore s;
+
+       s.va = memset32(engine->status_page.addr + 1000, 0, 1);
+       s.ggtt = (i915_ggtt_offset(engine->status_page.vma) +
+                 offset_in_page(s.va));
+
+       return s;
+}
+
+static u32 *emit_noops(u32 *cs, int count)
+{
+       while (count--)
+               *cs++ = MI_NOOP;
+
+       return cs;
+}
+
 static struct i915_request *
 record_registers(struct intel_context *ce,
+                struct intel_engine_cs *engine,
                 struct i915_vma *before,
                 struct i915_vma *after,
                 bool relative,
-                u32 *sema)
+                const struct hwsp_semaphore *sema)
 {
        struct i915_vma *b_before, *b_after;
        struct i915_request *rq;
        u32 *cs;
        int err;
 
-       b_before = store_context(ce, before, relative);
+       b_before = store_context(ce, engine, before, relative);
        if (IS_ERR(b_before))
                return ERR_CAST(b_before);
 
-       b_after = store_context(ce, after, relative);
+       b_after = store_context(ce, engine, after, relative);
        if (IS_ERR(b_after)) {
                rq = ERR_CAST(b_after);
                goto err_before;
@@ -1044,7 +1070,7 @@ record_registers(struct intel_context *ce,
        if (err)
                goto err_rq;
 
-       cs = intel_ring_begin(rq, 14);
+       cs = intel_ring_begin(rq, 18);
        if (IS_ERR(cs)) {
                err = PTR_ERR(cs);
                goto err_rq;
@@ -1055,16 +1081,28 @@ record_registers(struct intel_context *ce,
        *cs++ = lower_32_bits(b_before->node.start);
        *cs++ = upper_32_bits(b_before->node.start);
 
-       *cs++ = MI_ARB_ON_OFF | MI_ARB_ENABLE;
-       *cs++ = MI_SEMAPHORE_WAIT |
-               MI_SEMAPHORE_GLOBAL_GTT |
-               MI_SEMAPHORE_POLL |
-               MI_SEMAPHORE_SAD_NEQ_SDD;
-       *cs++ = 0;
-       *cs++ = i915_ggtt_offset(ce->engine->status_page.vma) +
-               offset_in_page(sema);
-       *cs++ = 0;
-       *cs++ = MI_NOOP;
+       if (sema) {
+               WRITE_ONCE(*sema->va, -1);
+
+               /* Signal the poisoner */
+               *cs++ = MI_STORE_DWORD_IMM_GEN4 | MI_USE_GGTT;
+               *cs++ = sema->ggtt;
+               *cs++ = 0;
+               *cs++ = 0;
+
+               /* Then wait for the poison to settle */
+               *cs++ = MI_ARB_ON_OFF | MI_ARB_ENABLE;
+               *cs++ = MI_SEMAPHORE_WAIT |
+                       MI_SEMAPHORE_GLOBAL_GTT |
+                       MI_SEMAPHORE_POLL |
+                       MI_SEMAPHORE_SAD_NEQ_SDD;
+               *cs++ = 0;
+               *cs++ = sema->ggtt;
+               *cs++ = 0;
+               *cs++ = MI_NOOP;
+       } else {
+               cs = emit_noops(cs, 10);
+       }
 
        *cs++ = MI_ARB_ON_OFF | MI_ARB_DISABLE;
        *cs++ = MI_BATCH_BUFFER_START_GEN8 | BIT(8);
@@ -1073,7 +1111,6 @@ record_registers(struct intel_context *ce,
 
        intel_ring_advance(rq, cs);
 
-       WRITE_ONCE(*sema, 0);
        i915_request_get(rq);
        i915_request_add(rq);
 err_after:
@@ -1089,7 +1126,9 @@ record_registers(struct intel_context *ce,
 }
 
 static struct i915_vma *
-load_context(struct intel_context *ce, u32 poison, bool relative)
+load_context(struct intel_context *ce,
+            struct intel_engine_cs *engine,
+            u32 poison, bool relative)
 {
        struct i915_vma *batch;
        u32 dw, *cs, *hw;
@@ -1105,7 +1144,7 @@ load_context(struct intel_context *ce, u32 poison, bool 
relative)
                return ERR_CAST(cs);
        }
 
-       defaults = shmem_pin_map(ce->engine->default_state);
+       defaults = shmem_pin_map(engine->default_state);
        if (!defaults) {
                i915_gem_object_unpin_map(batch->obj);
                i915_vma_put(batch);
@@ -1136,7 +1175,7 @@ load_context(struct intel_context *ce, u32 poison, bool 
relative)
                        if (relative)
                                cmd |= MI_LRI_LRM_CS_MMIO;
                        else
-                               offset = ce->engine->mmio_base;
+                               offset = engine->mmio_base;
                }
 
                dw++;
@@ -1152,7 +1191,7 @@ load_context(struct intel_context *ce, u32 poison, bool 
relative)
 
        *cs++ = MI_BATCH_BUFFER_END;
 
-       shmem_unpin_map(ce->engine->default_state, defaults);
+       shmem_unpin_map(engine->default_state, defaults);
 
        i915_gem_object_flush_map(batch->obj);
        i915_gem_object_unpin_map(batch->obj);
@@ -1162,16 +1201,17 @@ load_context(struct intel_context *ce, u32 poison, bool 
relative)
 
 static int
 poison_registers(struct intel_context *ce,
+                struct intel_engine_cs *engine,
                 u32 poison,
                 bool relative,
-                u32 *sema)
+                const struct hwsp_semaphore *sema)
 {
        struct i915_request *rq;
        struct i915_vma *batch;
        u32 *cs;
        int err;
 
-       batch = load_context(ce, poison, relative);
+       batch = load_context(ce, engine, poison, relative);
        if (IS_ERR(batch))
                return PTR_ERR(batch);
 
@@ -1185,20 +1225,29 @@ poison_registers(struct intel_context *ce,
        if (err)
                goto err_rq;
 
-       cs = intel_ring_begin(rq, 8);
+       cs = intel_ring_begin(rq, 14);
        if (IS_ERR(cs)) {
                err = PTR_ERR(cs);
                goto err_rq;
        }
 
+       *cs++ = MI_ARB_ON_OFF | MI_ARB_ENABLE;
+       *cs++ = MI_SEMAPHORE_WAIT |
+               MI_SEMAPHORE_GLOBAL_GTT |
+               MI_SEMAPHORE_POLL |
+               MI_SEMAPHORE_SAD_EQ_SDD;
+       *cs++ = 0;
+       *cs++ = sema->ggtt;
+       *cs++ = 0;
+       *cs++ = MI_NOOP;
+
        *cs++ = MI_ARB_ON_OFF | MI_ARB_DISABLE;
        *cs++ = MI_BATCH_BUFFER_START_GEN8 | BIT(8);
        *cs++ = lower_32_bits(batch->node.start);
        *cs++ = upper_32_bits(batch->node.start);
 
        *cs++ = MI_STORE_DWORD_IMM_GEN4 | MI_USE_GGTT;
-       *cs++ = i915_ggtt_offset(ce->engine->status_page.vma) +
-               offset_in_page(sema);
+       *cs++ = sema->ggtt;
        *cs++ = 0;
        *cs++ = 1;
 
@@ -1258,7 +1307,7 @@ static int compare_isolation(struct intel_engine_cs 
*engine,
        }
        lrc += LRC_STATE_OFFSET / sizeof(*hw);
 
-       defaults = shmem_pin_map(ce->engine->default_state);
+       defaults = shmem_pin_map(engine->default_state);
        if (!defaults) {
                err = -ENOMEM;
                goto err_lrc;
@@ -1311,7 +1360,7 @@ static int compare_isolation(struct intel_engine_cs 
*engine,
        } while (dw < PAGE_SIZE / sizeof(u32) &&
                 (hw[dw] & ~BIT(0)) != MI_BATCH_BUFFER_END);
 
-       shmem_unpin_map(ce->engine->default_state, defaults);
+       shmem_unpin_map(engine->default_state, defaults);
 err_lrc:
        i915_gem_object_unpin_map(ce->state->obj);
 err_B1:
@@ -1328,7 +1377,7 @@ static int compare_isolation(struct intel_engine_cs 
*engine,
 static int
 __lrc_isolation(struct intel_engine_cs *engine, u32 poison, bool relative)
 {
-       u32 *sema = memset32(engine->status_page.addr + 1000, 0, 1);
+       struct hwsp_semaphore sema = hwsp_semaphore(engine);
        struct i915_vma *ref[2], *result[2];
        struct intel_context *A, *B;
        struct i915_request *rq;
@@ -1356,15 +1405,12 @@ __lrc_isolation(struct intel_engine_cs *engine, u32 
poison, bool relative)
                goto err_ref0;
        }
 
-       rq = record_registers(A, ref[0], ref[1], relative, sema);
+       rq = record_registers(A, engine, ref[0], ref[1], relative, NULL);
        if (IS_ERR(rq)) {
                err = PTR_ERR(rq);
                goto err_ref1;
        }
 
-       WRITE_ONCE(*sema, 1);
-       wmb();
-
        if (i915_request_wait(rq, 0, HZ / 2) < 0) {
                i915_request_put(rq);
                err = -ETIME;
@@ -1384,15 +1430,15 @@ __lrc_isolation(struct intel_engine_cs *engine, u32 
poison, bool relative)
                goto err_result0;
        }
 
-       rq = record_registers(A, result[0], result[1], relative, sema);
+       rq = record_registers(A, engine, result[0], result[1], relative, &sema);
        if (IS_ERR(rq)) {
                err = PTR_ERR(rq);
                goto err_result1;
        }
 
-       err = poison_registers(B, poison, relative, sema);
+       err = poison_registers(B, engine, poison, relative, &sema);
        if (err) {
-               WRITE_ONCE(*sema, -1);
+               WRITE_ONCE(*sema.va, -1);
                i915_request_put(rq);
                goto err_result1;
        }
@@ -1494,6 +1540,160 @@ static int live_lrc_isolation(void *arg)
        return err;
 }
 
+static int __lrc_cross(struct intel_engine_cs *a,
+                      struct intel_engine_cs *b,
+                      u32 poison)
+{
+       struct hwsp_semaphore sema = hwsp_semaphore(a);
+       struct i915_vma *ref[2], *result[2];
+       struct intel_context *A, *B;
+       struct i915_request *rq;
+       int err;
+
+       GEM_BUG_ON(a->gt->ggtt != b->gt->ggtt);
+
+       pr_debug("Context on %s, poisoning from %s with %08x\n",
+                a->name, b->name, poison);
+
+       A = intel_context_create(a);
+       if (IS_ERR(A))
+               return PTR_ERR(A);
+
+       B = intel_context_create(b);
+       if (IS_ERR(B)) {
+               err = PTR_ERR(B);
+               goto err_A;
+       }
+
+       ref[0] = create_user_vma(A->vm, SZ_64K);
+       if (IS_ERR(ref[0])) {
+               err = PTR_ERR(ref[0]);
+               goto err_B;
+       }
+
+       ref[1] = create_user_vma(A->vm, SZ_64K);
+       if (IS_ERR(ref[1])) {
+               err = PTR_ERR(ref[1]);
+               goto err_ref0;
+       }
+
+       rq = record_registers(A, a, ref[0], ref[1], false, NULL);
+       if (IS_ERR(rq)) {
+               err = PTR_ERR(rq);
+               goto err_ref1;
+       }
+
+       if (i915_request_wait(rq, 0, HZ / 2) < 0) {
+               i915_request_put(rq);
+               err = -ETIME;
+               goto err_ref1;
+       }
+       i915_request_put(rq);
+
+       result[0] = create_user_vma(A->vm, SZ_64K);
+       if (IS_ERR(result[0])) {
+               err = PTR_ERR(result[0]);
+               goto err_ref1;
+       }
+
+       result[1] = create_user_vma(A->vm, SZ_64K);
+       if (IS_ERR(result[1])) {
+               err = PTR_ERR(result[1]);
+               goto err_result0;
+       }
+
+       rq = record_registers(A, a, result[0], result[1], false, &sema);
+       if (IS_ERR(rq)) {
+               err = PTR_ERR(rq);
+               goto err_result1;
+       }
+
+       err = poison_registers(B, a, poison, false, &sema);
+       if (err) {
+               WRITE_ONCE(*sema.va, -1);
+               i915_request_put(rq);
+               goto err_result1;
+       }
+
+       if (i915_request_wait(rq, 0, HZ / 2) < 0) {
+               i915_request_put(rq);
+               err = -ETIME;
+               goto err_result1;
+       }
+       i915_request_put(rq);
+
+       err = compare_isolation(a, ref, result, A, poison, false);
+
+err_result1:
+       i915_vma_put(result[1]);
+err_result0:
+       i915_vma_put(result[0]);
+err_ref1:
+       i915_vma_put(ref[1]);
+err_ref0:
+       i915_vma_put(ref[0]);
+err_B:
+       intel_context_put(B);
+err_A:
+       intel_context_put(A);
+       return err;
+}
+
+static int live_lrc_cross(void *arg)
+{
+       struct intel_gt *gt = arg;
+       struct intel_engine_cs *a, *b;
+       enum intel_engine_id a_id, b_id;
+       const u32 poison[] = {
+               STACK_MAGIC,
+               0x3a3a3a3a,
+               0x5c5c5c5c,
+               0xffffffff,
+               0xffff0000,
+       };
+       int err = 0;
+       int i;
+
+       /*
+        * Our goal is to try and tamper with another client's context
+        * running concurrently. The HW's goal is to stop us.
+        */
+
+       for_each_engine(a, gt, a_id) {
+               if (!IS_ENABLED(CONFIG_DRM_I915_SELFTEST_BROKEN) &&
+                   skip_isolation(a))
+                       continue;
+
+               intel_engine_pm_get(a);
+               for_each_engine(b, gt, b_id) {
+                       if (a == b)
+                               continue;
+
+                       intel_engine_pm_get(b);
+                       for (i = 0; i < ARRAY_SIZE(poison); i++) {
+                               int result;
+
+                               result = __lrc_cross(a, b, poison[i]);
+                               if (result && !err)
+                                       err = result;
+
+                               result = __lrc_cross(a, b, ~poison[i]);
+                               if (result && !err)
+                                       err = result;
+                       }
+                       intel_engine_pm_put(b);
+               }
+               intel_engine_pm_put(a);
+
+               if (igt_flush_test(gt->i915)) {
+                       err = -EIO;
+                       break;
+               }
+       }
+
+       return err;
+}
+
 static int indirect_ctx_submit_req(struct intel_context *ce)
 {
        struct i915_request *rq;
@@ -1884,6 +2084,7 @@ int intel_lrc_live_selftests(struct drm_i915_private 
*i915)
                SUBTEST(live_lrc_isolation),
                SUBTEST(live_lrc_timestamp),
                SUBTEST(live_lrc_garbage),
+               SUBTEST(live_lrc_cross),
                SUBTEST(live_pphwsp_runtime),
                SUBTEST(live_lrc_indirect_ctx_bb),
        };
-- 
2.20.1

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