linux-kernel - [PATCH] PCI: Exit restore process when device is still powerdown

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Message-ID: <20221222124104.69607-1-water.zhangjiantao@huawei.com>
Date:   Thu, 22 Dec 2022 12:41:04 +0000
From:   Jiantao Zhang <water.zhangjiantao@...wei.com>
To:     <bhelgaas@...gle.com>, <linux-pci@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <zhangjianrong5@...wei.com>
CC:     <suzhuangluan@...ilicon.com>, <caiyadong@...wei.com>,
        <guhengsheng@...ilicon.com>, <songxiaowei@...ilicon.com>,
        <water.zhangjiantao@...wei.com>
Subject: [PATCH] PCI: Exit restore process when device is still powerdown

We get this stack when the rp doesn't power up in resume noirq:
    dump_backtrace.cfi_jt+0x0/0x4
    dump_stack_lvl+0xb4/0x10c
    show_regs_before_dump_stack+0x1c/0x30
    arm64_serror_panic+0x110/0x1a8
    do_serror+0x16c/0x1cc
    el1_error+0x8c/0x10c
    do_raw_spin_unlock+0x74/0xdc
    pci_bus_read_config_word+0xdc/0x1dc
    pci_restore_msi_state+0x2f4/0x36c
    pci_restore_state+0x13f0/0x1444
    pci_pm_resume_noirq+0x158/0x318
    dpm_run_callback+0x178/0x5e8
    device_resume_noirq+0x250/0x264
    async_resume_noirq+0x20/0xf8
    async_run_entry_fn+0xfc/0x364
    process_one_work+0x37c/0x7f4
    worker_thread+0x3e8/0x754
    kthread+0x168/0x204
    ret_from_fork+0x10/0x18
The ep device uses msix, the restore process will write bar space
in __pci_msix_desc_mask_irq, which will result in accessing the
powerdown area when the rp doesn't power on.

It makes sense we should do nothing when the device is still powerdown.

Signed-off-by: Jianrong Zhang <zhangjianrong5@...wei.com>
Signed-off-by: Jiantao Zhang <water.zhangjiantao@...wei.com>
---
 drivers/pci/pci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index fba95486caaf..279f6e8c5a00 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1764,7 +1764,7 @@ static void pci_restore_rebar_state(struct pci_dev *pdev)
  */
 void pci_restore_state(struct pci_dev *dev)
 {
-	if (!dev->state_saved)
+	if (!dev->state_saved || dev->current_state == PCI_UNKNOWN)
 		return;
 
 	/*
-- 
2.17.1