From: Ajit Khaparde <ajit.khaparde(a)broadcom.com>
[ Upstream commit 524e057b2d66b61f9b63b6db30467ab7b0bb4796 ]
The Broadcom BCM5760X NIC may be a multi-function device.
While it does not advertise an ACS capability, peer-to-peer transactions
are not possible between the individual functions. So it is ok to treat
them as fully isolated.
Add an ACS quirk for this device so the functions can be in independent
IOMMU groups and attached individually to userspace applications using
VFIO.
[kwilczynski: commit log]
Link: https://lore.kernel.org/linux-pci/20240510204228.73435-1-ajit.khaparde@broa…
Signed-off-by: Ajit Khaparde <ajit.khaparde(a)broadcom.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski(a)kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas(a)google.com>
Reviewed-by: Andy Gospodarek <gospo(a)broadcom.com>
Signed-off-by: Sasha Levin <sashal(a)kernel.org>
---
drivers/pci/quirks.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 4d4267105cd2b..842e8fecf0a9a 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -4971,6 +4971,10 @@ static const struct pci_dev_acs_enabled {
{ PCI_VENDOR_ID_BROADCOM, 0x1750, pci_quirk_mf_endpoint_acs },
{ PCI_VENDOR_ID_BROADCOM, 0x1751, pci_quirk_mf_endpoint_acs },
{ PCI_VENDOR_ID_BROADCOM, 0x1752, pci_quirk_mf_endpoint_acs },
+ { PCI_VENDOR_ID_BROADCOM, 0x1760, pci_quirk_mf_endpoint_acs },
+ { PCI_VENDOR_ID_BROADCOM, 0x1761, pci_quirk_mf_endpoint_acs },
+ { PCI_VENDOR_ID_BROADCOM, 0x1762, pci_quirk_mf_endpoint_acs },
+ { PCI_VENDOR_ID_BROADCOM, 0x1763, pci_quirk_mf_endpoint_acs },
{ PCI_VENDOR_ID_BROADCOM, 0xD714, pci_quirk_brcm_acs },
/* Amazon Annapurna Labs */
{ PCI_VENDOR_ID_AMAZON_ANNAPURNA_LABS, 0x0031, pci_quirk_al_acs },
--
2.43.0
File-scope "__pmic_glink_lock" mutex protects the filke-scope
"__pmic_glink", thus reference to it should be obtained under the lock,
just like pmic_glink_rpmsg_remove() is doing. Otherwise we have a race
during if PMIC GLINK device removal: the pmic_glink_rpmsg_probe()
function could store local reference before mutex in driver removal is
acquired.
Fixes: 58ef4ece1e41 ("soc: qcom: pmic_glink: Introduce base PMIC GLINK driver")
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski(a)linaro.org>
---
Changes in v2:
1. None
---
drivers/soc/qcom/pmic_glink.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/soc/qcom/pmic_glink.c b/drivers/soc/qcom/pmic_glink.c
index 9606222993fd..452f30a9354d 100644
--- a/drivers/soc/qcom/pmic_glink.c
+++ b/drivers/soc/qcom/pmic_glink.c
@@ -217,10 +217,11 @@ static void pmic_glink_pdr_callback(int state, char *svc_path, void *priv)
static int pmic_glink_rpmsg_probe(struct rpmsg_device *rpdev)
{
- struct pmic_glink *pg = __pmic_glink;
+ struct pmic_glink *pg;
int ret = 0;
mutex_lock(&__pmic_glink_lock);
+ pg = __pmic_glink;
if (!pg) {
ret = dev_err_probe(&rpdev->dev, -ENODEV, "no pmic_glink device to attach to\n");
goto out_unlock;
--
2.43.0
The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 24a9799aa8efecd0eb55a75e35f9d8e6400063aa
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2024040834-magazine-audience-8aa4@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..
Possible dependencies:
24a9799aa8ef ("smb: client: fix UAF in smb2_reconnect_server()")
7257bcf3bdc7 ("cifs: cifs_chan_is_iface_active should be called with chan_lock held")
27e1fd343f80 ("cifs: after disabling multichannel, mark tcon for reconnect")
fa1d0508bdd4 ("cifs: account for primary channel in the interface list")
a6d8fb54a515 ("cifs: distribute channels across interfaces based on speed")
c37ed2d7d098 ("smb: client: remove extra @chan_count check in __cifs_put_smb_ses()")
ff7d80a9f271 ("cifs: fix session state transition to avoid use-after-free issue")
38c8a9a52082 ("smb: move client and server files to common directory fs/smb")
943fb67b0902 ("cifs: missing lock when updating session status")
bc962159e8e3 ("cifs: avoid race conditions with parallel reconnects")
1bcd548d935a ("cifs: prevent data race in cifs_reconnect_tcon()")
e77978de4765 ("cifs: update ip_addr for ses only for primary chan setup")
3c0070f54b31 ("cifs: prevent data race in smb2_reconnect()")
05844bd661d9 ("cifs: print last update time for interface list")
25cf01b7c920 ("cifs: set correct status of tcon ipc when reconnecting")
abdb1742a312 ("cifs: get rid of mount options string parsing")
9fd29a5bae6e ("cifs: use fs_context for automounts")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 24a9799aa8efecd0eb55a75e35f9d8e6400063aa Mon Sep 17 00:00:00 2001
From: Paulo Alcantara <pc(a)manguebit.com>
Date: Mon, 1 Apr 2024 14:13:10 -0300
Subject: [PATCH] smb: client: fix UAF in smb2_reconnect_server()
The UAF bug is due to smb2_reconnect_server() accessing a session that
is already being teared down by another thread that is executing
__cifs_put_smb_ses(). This can happen when (a) the client has
connection to the server but no session or (b) another thread ends up
setting @ses->ses_status again to something different than
SES_EXITING.
To fix this, we need to make sure to unconditionally set
@ses->ses_status to SES_EXITING and prevent any other threads from
setting a new status while we're still tearing it down.
The following can be reproduced by adding some delay to right after
the ipc is freed in __cifs_put_smb_ses() - which will give
smb2_reconnect_server() worker a chance to run and then accessing
@ses->ipc:
kinit ...
mount.cifs //srv/share /mnt/1 -o sec=krb5,nohandlecache,echo_interval=10
[disconnect srv]
ls /mnt/1 &>/dev/null
sleep 30
kdestroy
[reconnect srv]
sleep 10
umount /mnt/1
...
CIFS: VFS: Verify user has a krb5 ticket and keyutils is installed
CIFS: VFS: \\srv Send error in SessSetup = -126
CIFS: VFS: Verify user has a krb5 ticket and keyutils is installed
CIFS: VFS: \\srv Send error in SessSetup = -126
general protection fault, probably for non-canonical address
0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP NOPTI
CPU: 3 PID: 50 Comm: kworker/3:1 Not tainted 6.9.0-rc2 #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-1.fc39
04/01/2014
Workqueue: cifsiod smb2_reconnect_server [cifs]
RIP: 0010:__list_del_entry_valid_or_report+0x33/0xf0
Code: 4f 08 48 85 d2 74 42 48 85 c9 74 59 48 b8 00 01 00 00 00 00 ad
de 48 39 c2 74 61 48 b8 22 01 00 00 00 00 74 69 <48> 8b 01 48 39 f8 75
7b 48 8b 72 08 48 39 c6 0f 85 88 00 00 00 b8
RSP: 0018:ffffc900001bfd70 EFLAGS: 00010a83
RAX: dead000000000122 RBX: ffff88810da53838 RCX: 6b6b6b6b6b6b6b6b
RDX: 6b6b6b6b6b6b6b6b RSI: ffffffffc02f6878 RDI: ffff88810da53800
RBP: ffff88810da53800 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff88810c064000
R13: 0000000000000001 R14: ffff88810c064000 R15: ffff8881039cc000
FS: 0000000000000000(0000) GS:ffff888157c00000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe3728b1000 CR3: 000000010caa4000 CR4: 0000000000750ef0
PKRU: 55555554
Call Trace:
<TASK>
? die_addr+0x36/0x90
? exc_general_protection+0x1c1/0x3f0
? asm_exc_general_protection+0x26/0x30
? __list_del_entry_valid_or_report+0x33/0xf0
__cifs_put_smb_ses+0x1ae/0x500 [cifs]
smb2_reconnect_server+0x4ed/0x710 [cifs]
process_one_work+0x205/0x6b0
worker_thread+0x191/0x360
? __pfx_worker_thread+0x10/0x10
kthread+0xe2/0x110
? __pfx_kthread+0x10/0x10
ret_from_fork+0x34/0x50
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
Cc: stable(a)vger.kernel.org
Signed-off-by: Paulo Alcantara (Red Hat) <pc(a)manguebit.com>
Signed-off-by: Steve French <stfrench(a)microsoft.com>
diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
index 9b85b5341822..ee29bc57300c 100644
--- a/fs/smb/client/connect.c
+++ b/fs/smb/client/connect.c
@@ -232,7 +232,13 @@ cifs_mark_tcp_ses_conns_for_reconnect(struct TCP_Server_Info *server,
spin_lock(&cifs_tcp_ses_lock);
list_for_each_entry_safe(ses, nses, &pserver->smb_ses_list, smb_ses_list) {
- /* check if iface is still active */
+ spin_lock(&ses->ses_lock);
+ if (ses->ses_status == SES_EXITING) {
+ spin_unlock(&ses->ses_lock);
+ continue;
+ }
+ spin_unlock(&ses->ses_lock);
+
spin_lock(&ses->chan_lock);
if (cifs_ses_get_chan_index(ses, server) ==
CIFS_INVAL_CHAN_INDEX) {
@@ -1963,31 +1969,6 @@ cifs_setup_ipc(struct cifs_ses *ses, struct smb3_fs_context *ctx)
return rc;
}
-/**
- * cifs_free_ipc - helper to release the session IPC tcon
- * @ses: smb session to unmount the IPC from
- *
- * Needs to be called everytime a session is destroyed.
- *
- * On session close, the IPC is closed and the server must release all tcons of the session.
- * No need to send a tree disconnect here.
- *
- * Besides, it will make the server to not close durable and resilient files on session close, as
- * specified in MS-SMB2 3.3.5.6 Receiving an SMB2 LOGOFF Request.
- */
-static int
-cifs_free_ipc(struct cifs_ses *ses)
-{
- struct cifs_tcon *tcon = ses->tcon_ipc;
-
- if (tcon == NULL)
- return 0;
-
- tconInfoFree(tcon);
- ses->tcon_ipc = NULL;
- return 0;
-}
-
static struct cifs_ses *
cifs_find_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
{
@@ -2019,48 +2000,52 @@ cifs_find_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
void __cifs_put_smb_ses(struct cifs_ses *ses)
{
struct TCP_Server_Info *server = ses->server;
+ struct cifs_tcon *tcon;
unsigned int xid;
size_t i;
+ bool do_logoff;
int rc;
- spin_lock(&ses->ses_lock);
- if (ses->ses_status == SES_EXITING) {
- spin_unlock(&ses->ses_lock);
- return;
- }
- spin_unlock(&ses->ses_lock);
-
- cifs_dbg(FYI, "%s: ses_count=%d\n", __func__, ses->ses_count);
- cifs_dbg(FYI,
- "%s: ses ipc: %s\n", __func__, ses->tcon_ipc ? ses->tcon_ipc->tree_name : "NONE");
-
spin_lock(&cifs_tcp_ses_lock);
- if (--ses->ses_count > 0) {
+ spin_lock(&ses->ses_lock);
+ cifs_dbg(FYI, "%s: id=0x%llx ses_count=%d ses_status=%u ipc=%s\n",
+ __func__, ses->Suid, ses->ses_count, ses->ses_status,
+ ses->tcon_ipc ? ses->tcon_ipc->tree_name : "none");
+ if (ses->ses_status == SES_EXITING || --ses->ses_count > 0) {
+ spin_unlock(&ses->ses_lock);
spin_unlock(&cifs_tcp_ses_lock);
return;
}
- spin_lock(&ses->ses_lock);
- if (ses->ses_status == SES_GOOD)
- ses->ses_status = SES_EXITING;
- spin_unlock(&ses->ses_lock);
- spin_unlock(&cifs_tcp_ses_lock);
-
/* ses_count can never go negative */
WARN_ON(ses->ses_count < 0);
- spin_lock(&ses->ses_lock);
- if (ses->ses_status == SES_EXITING && server->ops->logoff) {
- spin_unlock(&ses->ses_lock);
- cifs_free_ipc(ses);
+ spin_lock(&ses->chan_lock);
+ cifs_chan_clear_need_reconnect(ses, server);
+ spin_unlock(&ses->chan_lock);
+
+ do_logoff = ses->ses_status == SES_GOOD && server->ops->logoff;
+ ses->ses_status = SES_EXITING;
+ tcon = ses->tcon_ipc;
+ ses->tcon_ipc = NULL;
+ spin_unlock(&ses->ses_lock);
+ spin_unlock(&cifs_tcp_ses_lock);
+
+ /*
+ * On session close, the IPC is closed and the server must release all
+ * tcons of the session. No need to send a tree disconnect here.
+ *
+ * Besides, it will make the server to not close durable and resilient
+ * files on session close, as specified in MS-SMB2 3.3.5.6 Receiving an
+ * SMB2 LOGOFF Request.
+ */
+ tconInfoFree(tcon);
+ if (do_logoff) {
xid = get_xid();
rc = server->ops->logoff(xid, ses);
if (rc)
cifs_server_dbg(VFS, "%s: Session Logoff failure rc=%d\n",
__func__, rc);
_free_xid(xid);
- } else {
- spin_unlock(&ses->ses_lock);
- cifs_free_ipc(ses);
}
spin_lock(&cifs_tcp_ses_lock);
read_hv_sched_clock_tsc() assumes that the Hyper-V clock counter is
bigger than the variable hv_sched_clock_offset, which is cached during
early boot, but depending on the timing this assumption may be false
when a hibernated VM starts again (the clock counter starts from 0
again) and is resuming back (Note: hv_init_tsc_clocksource() is not
called during hibernation/resume); consequently,
read_hv_sched_clock_tsc() may return a negative integer (which is
interpreted as a huge positive integer since the return type is u64)
and new kernel messages are prefixed with huge timestamps before
read_hv_sched_clock_tsc() grows big enough (which typically takes
several seconds).
Fix the issue by saving the Hyper-V clock counter just before the
suspend, and using it to correct the hv_sched_clock_offset in
resume. This makes hv tsc page based sched_clock continuous and ensures
that post resume, it starts from where it left off during suspend.
Override x86_platform.save_sched_clock_state and
x86_platform.restore_sched_clock_state routines to correct this as soon
as possible.
Note: if Invariant TSC is available, the issue doesn't happen because
1) we don't register read_hv_sched_clock_tsc() for sched clock:
See commit e5313f1c5404 ("clocksource/drivers/hyper-v: Rework
clocksource and sched clock setup");
2) the common x86 code adjusts TSC similarly: see
__restore_processor_state() -> tsc_verify_tsc_adjust(true) and
x86_platform.restore_sched_clock_state().
Cc: stable(a)vger.kernel.org
Fixes: 1349401ff1aa ("clocksource/drivers/hyper-v: Suspend/resume Hyper-V clocksource for hibernation")
Co-developed-by: Dexuan Cui <decui(a)microsoft.com>
Signed-off-by: Dexuan Cui <decui(a)microsoft.com>
Signed-off-by: Naman Jain <namjain(a)linux.microsoft.com>
---
Changes from v2:
https://lore.kernel.org/all/20240911045632.3757-1-namjain@linux.microsoft.c…
Addressed Michael's comments:
* Changed commit msg to include information on making timestamps
continuous
* Changed subject to reflect the new file being changed
* Changed variable name for saving offset/counters
* Moved comment on new function introduced from header file to function
definition.
* Removed the equations in comments
* Rebased to latest linux-next tip
Changes from v1:
https://lore.kernel.org/all/20240909053923.8512-1-namjain@linux.microsoft.c…
* Reorganized code as per Michael's comment, and moved the logic to x86
specific files, to keep hyperv_timer.c arch independent.
---
arch/x86/kernel/cpu/mshyperv.c | 58 ++++++++++++++++++++++++++++++
drivers/clocksource/hyperv_timer.c | 14 +++++++-
include/clocksource/hyperv_timer.h | 2 ++
3 files changed, 73 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index ead967479fa6..e8e25d6e64cd 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -224,6 +224,63 @@ static void hv_machine_crash_shutdown(struct pt_regs *regs)
hyperv_cleanup();
}
#endif /* CONFIG_CRASH_DUMP */
+
+static u64 hv_ref_counter_at_suspend;
+static void (*old_save_sched_clock_state)(void);
+static void (*old_restore_sched_clock_state)(void);
+
+/*
+ * Hyper-V clock counter resets during hibernation. Save and restore clock
+ * offset during suspend/resume, while also considering the time passed
+ * before suspend. This is to make sure that sched_clock using hv tsc page
+ * based clocksource, proceeds from where it left off during suspend and
+ * it shows correct time for the timestamps of kernel messages after resume.
+ */
+static void save_hv_clock_tsc_state(void)
+{
+ hv_ref_counter_at_suspend = hv_read_reference_counter();
+}
+
+static void restore_hv_clock_tsc_state(void)
+{
+ /*
+ * Adjust the offsets used by hv tsc clocksource to
+ * account for the time spent before hibernation.
+ * adjusted value = reference counter (time) at suspend
+ * - reference counter (time) now.
+ */
+ hv_adj_sched_clock_offset(hv_ref_counter_at_suspend - hv_read_reference_counter());
+}
+
+/*
+ * Functions to override save_sched_clock_state and restore_sched_clock_state
+ * functions of x86_platform. The Hyper-V clock counter is reset during
+ * suspend-resume and the offset used to measure time needs to be
+ * corrected, post resume.
+ */
+static void hv_save_sched_clock_state(void)
+{
+ old_save_sched_clock_state();
+ save_hv_clock_tsc_state();
+}
+
+static void hv_restore_sched_clock_state(void)
+{
+ restore_hv_clock_tsc_state();
+ old_restore_sched_clock_state();
+}
+
+static void __init x86_setup_ops_for_tsc_pg_clock(void)
+{
+ if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
+ return;
+
+ old_save_sched_clock_state = x86_platform.save_sched_clock_state;
+ x86_platform.save_sched_clock_state = hv_save_sched_clock_state;
+
+ old_restore_sched_clock_state = x86_platform.restore_sched_clock_state;
+ x86_platform.restore_sched_clock_state = hv_restore_sched_clock_state;
+}
#endif /* CONFIG_HYPERV */
static uint32_t __init ms_hyperv_platform(void)
@@ -590,6 +647,7 @@ static void __init ms_hyperv_init_platform(void)
/* Register Hyper-V specific clocksource */
hv_init_clocksource();
+ x86_setup_ops_for_tsc_pg_clock();
hv_vtl_init_platform();
#endif
/*
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index 99177835cade..b39dee7b93af 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -27,7 +27,8 @@
#include <asm/mshyperv.h>
static struct clock_event_device __percpu *hv_clock_event;
-static u64 hv_sched_clock_offset __ro_after_init;
+/* Note: offset can hold negative values after hibernation. */
+static u64 hv_sched_clock_offset __read_mostly;
/*
* If false, we're using the old mechanism for stimer0 interrupts
@@ -470,6 +471,17 @@ static void resume_hv_clock_tsc(struct clocksource *arg)
hv_set_msr(HV_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
}
+/*
+ * Called during resume from hibernation, from overridden
+ * x86_platform.restore_sched_clock_state routine. This is to adjust offsets
+ * used to calculate time for hv tsc page based sched_clock, to account for
+ * time spent before hibernation.
+ */
+void hv_adj_sched_clock_offset(u64 offset)
+{
+ hv_sched_clock_offset -= offset;
+}
+
#ifdef HAVE_VDSO_CLOCKMODE_HVCLOCK
static int hv_cs_enable(struct clocksource *cs)
{
diff --git a/include/clocksource/hyperv_timer.h b/include/clocksource/hyperv_timer.h
index 6cdc873ac907..aa5233b1eba9 100644
--- a/include/clocksource/hyperv_timer.h
+++ b/include/clocksource/hyperv_timer.h
@@ -38,6 +38,8 @@ extern void hv_remap_tsc_clocksource(void);
extern unsigned long hv_get_tsc_pfn(void);
extern struct ms_hyperv_tsc_page *hv_get_tsc_page(void);
+extern void hv_adj_sched_clock_offset(u64 offset);
+
static __always_inline bool
hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
u64 *cur_tsc, u64 *time)
base-commit: a430d95c5efa2b545d26a094eb5f624e36732af0
--
2.34.1
Leonard Lausen reported an issue with suspend/resume of the sc7180
devices. Fix the WB atomic check, which caused the issue. Also make sure
that DPU debugging logs are always directed to the drm_debug / DRIVER so
that usual drm.debug masks work in an expected way.
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov(a)linaro.org>
---
Changes in v2:
- Reworked the writeback to just drop the connector->status check.
- Expanded commit message for the debugging patch.
- Link to v1: https://lore.kernel.org/r/20240709-dpu-fix-wb-v1-0-448348bfd4cb@linaro.org
---
Dmitry Baryshkov (2):
drm/msm/dpu1: don't choke on disabling the writeback connector
drm/msm/dpu: don't play tricks with debug macros
drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h | 14 ++------------
drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c | 3 ---
2 files changed, 2 insertions(+), 15 deletions(-)
---
base-commit: 668d33c9ff922c4590c58754ab064aaf53c387dd
change-id: 20240709-dpu-fix-wb-6cd57e3eb182
Best regards,
--
Dmitry Baryshkov <dmitry.baryshkov(a)linaro.org>
Hi Greg, Sasha,
Please cherry pick upstream commit b17ef04bf3a4 ("drm/amd/display:
Pass pwrseq inst for backlight and ABM") to stable kernel 6.6.x and
newer.
This fixes broken backlight adjustment on some AMD platforms with eDP panels.
Thanks,
Alex