[PATCH AUTOSEL 5.6 088/149] drm/amd/display: System crashes when add_ptb_to_table() gets called

Sasha Levin
2020-04-11T23:05:42Z

From: Peikang Zhang <peikang.zhang@amd.com>

[ Upstream commit 0062972b9d9f888d0273c6496769d02e8f509135 ]

[Why]
Unused VMIDs were not evicted correctly

[How]
1. evict_vmids() logic was fixed;
2. Added boundary check for add_ptb_to_table() and
clear_entry_from_vmid_table() to avoid crash caused by array out of
boundary;
3. For mod_vmid_get_for_ptb(), vimd is changed from unsigned to signed
due to vimd is signed.

Signed-off-by: Peikang Zhang <peikang.zhang@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/amd/display/modules/vmid/vmid.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/modules/vmid/vmid.c b/drivers/gpu/drm/amd/display/modules/vmid/vmid.c
index f0a153704f6e0..00f132f8ad55d 100644
--- a/drivers/gpu/drm/amd/display/modules/vmid/vmid.c
+++ b/drivers/gpu/drm/amd/display/modules/vmid/vmid.c
@@ -40,14 +40,18 @@ struct core_vmid {

static void add_ptb_to_table(struct core_vmid *core_vmid, unsigned int vmid, uint64_t ptb)
{
- core_vmid->ptb_assigned_to_vmid[vmid] = ptb;
- core_vmid->num_vmids_available--;
+ if (vmid < MAX_VMID) {
+ core_vmid->ptb_assigned_to_vmid[vmid] = ptb;
+ core_vmid->num_vmids_available--;
+ }
}

static void clear_entry_from_vmid_table(struct core_vmid *core_vmid, unsigned int vmid)
{
- core_vmid->ptb_assigned_to_vmid[vmid] = 0;
- core_vmid->num_vmids_available++;
+ if (vmid < MAX_VMID) {
+ core_vmid->ptb_assigned_to_vmid[vmid] = 0;
+ core_vmid->num_vmids_available++;
+ }
}

static void evict_vmids(struct core_vmid *core_vmid)
@@ -57,7 +61,7 @@ static void evict_vmids(struct core_vmid *core_vmid)

// At this point any positions with value 0 are unused vmids, evict them
for (i = 1; i < core_vmid->num_vmid; i++) {
- if (ord & (1u << i))
+ if (!(ord & (1u << i)))
clear_entry_from_vmid_table(core_vmid, i);
}
}
@@ -91,7 +95,7 @@ static int get_next_available_vmid(struct core_vmid *core_vmid)
uint8_t mod_vmid_get_for_ptb(struct mod_vmid *mod_vmid, uint64_t ptb)
{
struct core_vmid *core_vmid = MOD_VMID_TO_CORE(mod_vmid);
- unsigned int vmid = 0;
+ int vmid = 0;

// Physical address gets vmid 0
if (ptb == 0)
--
2.20.1