From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefano Stabellini Subject: Re: [PATCH v2 01/16] Xen: ACPI: Hide UART used by Xen Date: Fri, 15 Jan 2016 15:39:54 +0000 Message-ID: References: <1452840929-19612-1-git-send-email-zhaoshenglong@huawei.com> <1452840929-19612-2-git-send-email-zhaoshenglong@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Return-path: In-Reply-To: <1452840929-19612-2-git-send-email-zhaoshenglong-hv44wF8Li93QT0dZR+AlfA@public.gmane.org> Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Shannon Zhao Cc: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, stefano.stabellini-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org, david.vrabel-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org, catalin.marinas-5wv7dgnIgG8@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, julien.grall-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org, xen-devel-GuqFBffKawuEi8DpZVb4nw@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, shannon.zhao-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, peter.huangpeng-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, "Rafael J. Wysocki" , Len Brown , "open list:ACPI" List-Id: linux-efi@vger.kernel.org On Fri, 15 Jan 2016, Shannon Zhao wrote: > From: Shannon Zhao > > ACPI 6.0 introduces a new table STAO to list the devices which are used > by Xen and can't be used by Dom0. On Xen virtual platforms, the physical > UART is used by Xen. So here it hides UART from Dom0. > > Signed-off-by: Shannon Zhao > --- > CC: "Rafael J. Wysocki" (supporter:ACPI) > CC: Len Brown (supporter:ACPI) > CC: linux-acpi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org (open list:ACPI) > --- > drivers/acpi/bus.c | 30 ++++++++++++++++++++++++++++++ > 1 file changed, 30 insertions(+) > > diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c > index a212cef..d7a559f 100644 > --- a/drivers/acpi/bus.c > +++ b/drivers/acpi/bus.c > @@ -46,6 +46,7 @@ ACPI_MODULE_NAME("bus"); > struct acpi_device *acpi_root; > struct proc_dir_entry *acpi_root_dir; > EXPORT_SYMBOL(acpi_root_dir); > +static u64 spcr_uart_addr; > > #ifdef CONFIG_X86 > #ifdef CONFIG_ACPI_CUSTOM_DSDT > @@ -93,6 +94,17 @@ acpi_status acpi_bus_get_status_handle(acpi_handle handle, > { > acpi_status status; > > + if (spcr_uart_addr != 0xffffffffffffffff) { Please #define something like EFI_INVALID_TABLE_ADDR and use it here instead of 0xffffffffffffffff for readability. Also spcr_uart_addr could be initialized where it is defined. Maybe it could be better to move this check into a separate function and only call acpi_set_device_status if spcr_uart_addr != addr? > + u64 addr; > + > + status = acpi_evaluate_integer(handle, METHOD_NAME__ADR, NULL, > + &addr); > + if (ACPI_SUCCESS(status) && (addr == spcr_uart_addr)) { > + *sta = 0; > + return AE_OK; > + } > + } > + > status = acpi_evaluate_integer(handle, "_STA", NULL, sta); > if (ACPI_SUCCESS(status)) > return AE_OK; > @@ -1069,6 +1081,8 @@ EXPORT_SYMBOL_GPL(acpi_kobj); > static int __init acpi_init(void) > { > int result; > + acpi_status status; > + struct acpi_table_stao *stao_ptr; > > if (acpi_disabled) { > printk(KERN_INFO PREFIX "Interpreter disabled.\n"); > @@ -1081,6 +1095,22 @@ static int __init acpi_init(void) > acpi_kobj = NULL; > } > > + /* If there is STAO table, check whether it needs to ignore the UART > + * device in SPCR table. > + */ > + spcr_uart_addr = 0xffffffffffffffff; > + status = acpi_get_table(ACPI_SIG_STAO, 0, > + (struct acpi_table_header **)&stao_ptr); > + if (ACPI_SUCCESS(status)) { > + if (stao_ptr->ignore_uart) { if (ACPI_SUCCESS(status) && stao_ptr->ignore_uart) { > + struct acpi_table_spcr *spcr_ptr; > + > + acpi_get_table(ACPI_SIG_SPCR, 0, > + (struct acpi_table_header **)&spcr_ptr); Maybe we should check that acpi_get_table succeeded, even though it should at this point. > + spcr_uart_addr = spcr_ptr->serial_port.address; > + } > + } > + > init_acpi_device_notify(); > result = acpi_bus_init(); > if (result) {