| Message ID | 20221118020013.125987-1-jiamei.xie@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | | expand |
diff --git a/xen/arch/arm/vpl011.c b/xen/arch/arm/vpl011.c index 43522d48fd..80d00b3052 100644 --- a/xen/arch/arm/vpl011.c +++ b/xen/arch/arm/vpl011.c @@ -463,6 +463,7 @@ static int vpl011_mmio_write(struct vcpu *v, case FR: case RIS: case MIS: + case DMACR: goto write_ignore; case IMSC:
Date: Thu, 17 Nov 2022 11:07:12 +0800 Subject: [PATCH] xen/arm: vpl011: Make access to DMACR write-ignore When the guest kernel enables DMA engine with "CONFIG_DMA_ENGINE=y", Linux SBSA PL011 driver will access PL011 DMACR register in some functions. As chapter "B Generic UART" in "ARM Server Base System Architecture"[1] documentation describes, SBSA UART doesn't support DMA. In current code, when the kernel tries to access DMACR register, Xen will inject a data abort: Unhandled fault at 0xffffffc00944d048 Mem abort info: ESR = 0x96000000 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x00: ttbr address size fault Data abort info: ISV = 0, ISS = 0x00000000 CM = 0, WnR = 0 swapper pgtable: 4k pages, 39-bit VAs, pgdp=0000000020e2e000 [ffffffc00944d048] pgd=100000003ffff803, p4d=100000003ffff803, pud=100000003ffff803, pmd=100000003fffa803, pte=006800009c090f13 Internal error: ttbr address size fault: 96000000 [#1] PREEMPT SMP ... Call trace: pl011_stop_rx+0x70/0x80 tty_port_shutdown+0x7c/0xb4 tty_port_close+0x60/0xcc uart_close+0x34/0x8c tty_release+0x144/0x4c0 __fput+0x78/0x220 ____fput+0x1c/0x30 task_work_run+0x88/0xc0 do_notify_resume+0x8d0/0x123c el0_svc+0xa8/0xc0 el0t_64_sync_handler+0xa4/0x130 el0t_64_sync+0x1a0/0x1a4 Code: b9000083 b901f001 794038a0 8b000042 (b9000041) ---[ end trace 83dd93df15c3216f ]--- note: bootlogd[132] exited with preempt_count 1 /etc/rcS.d/S07bootlogd: line 47: 132 Segmentation fault start-stop-daemon As discussed in [2], this commit makes the access to DMACR register write-ignore as an improvement. [1] https://developer.arm.com/documentation/den0094/c/?lang=en [2] https://lore.kernel.org/xen-devel/alpine.DEB.2.22.394.2211161552420.4020@ubuntu-linux-20-04-desktop/ Signed-off-by: Jiamei Xie <jiamei.xie@arm.com> --- xen/arch/arm/vpl011.c | 1 + 1 file changed, 1 insertion(+)