From mboxrd@z Thu Jan 1 00:00:00 1970 From: Parth Dixit Subject: Re: [PATCH v2 08/41] arm/acpi : Parse FADT table and get PSCI flags Date: Sun, 5 Jul 2015 18:35:21 +0530 Message-ID: References: <1431893048-5214-1-git-send-email-parth.dixit@linaro.org> <1431893048-5214-9-git-send-email-parth.dixit@linaro.org> <5559FE00.4070107@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Julien Grall Cc: keir@xen.org, Ian Campbell , andrew.cooper3@citrix.com, tim@xen.org, xen-devel , Stefano Stabellini , shannon.zhao@linaro.org, Jan Beulich , Christoffer Dall List-Id: xen-devel@lists.xenproject.org +shannon On 24 May 2015 at 11:35, Parth Dixit wrote: > > > On 18 May 2015 at 20:28, Julien Grall wrote: >> >> Hi Parth, >> >> On 17/05/15 21:03, Parth Dixit wrote: >> > There are two flags: PSCI_COMPLIANT and PSCI_USE_HVC. When set, >> > the former signals to the OS that the hardware is PSCI compliant. >> > The latter selects the appropriate conduit for PSCI calls by >> > toggling between Hypervisor Calls (HVC) and Secure Monitor Calls >> > (SMC). >> > >> > FADT table contains such information, parse FADT to get the flags >> > for furture usage. At the same time, only ACPI 5.1 or higher verison >> > supports PSCI, and FADT Major.Minor version was introduced in ACPI >> > 5.1, so we will check the version and only parse FADT table with >> > version >= 5.1. >> > >> > If firmware provides ACPI tables with ACPI version less than 5.1, >> > OS will be messed up with those information, so disable ACPI if we >> > get an FADT table with version less that 5.1. >> > >> > Modify FADT table before passing it to Dom0. >> > Set PSCI_COMPLIANT and PSCI_USE_HVC. >> > >> > Signed-off-by: Hanjun Guo >> > Signed-off-by: Naresh Bhat >> > Signed-off-by: Parth Dixit >> > --- >> > xen/arch/arm/acpi/boot.c | 38 ++++++++++++++++++++++++++++++++++++++ >> > xen/arch/arm/acpi/lib.c | 11 +++++++++++ >> > xen/include/asm-arm/acpi.h | 11 +++++++++++ >> > 3 files changed, 60 insertions(+) >> > >> > diff --git a/xen/arch/arm/acpi/boot.c b/xen/arch/arm/acpi/boot.c >> > index 8dc69d5..57eb33c 100644 >> > --- a/xen/arch/arm/acpi/boot.c >> > +++ b/xen/arch/arm/acpi/boot.c >> > @@ -24,9 +24,40 @@ >> > >> > #include >> > #include >> > +#include >> > +#include >> > +#include >> > >> > #include >> > >> > +static int __init acpi_parse_fadt(struct acpi_table_header *table) >> > +{ >> > + struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table; >> > + u8 checksum; >> > + >> > + /* >> > + * Revision in table header is the FADT Major revision, and there >> > + * is a minor revision of FADT which was introduced by ACPI 5.1, >> > + * we only deal with ACPI 5.1 or newer revision to get GIC and SMP >> > + * boot protocol configuration data, or we will disable ACPI. >> > + */ >> > + if ( table->revision > 5 || >> > + ( table->revision == 5 && fadt->minor_revision >= 1 ) ) >> >> The indentation looks wrong here. >> >> > + { >> > + fadt->arm_boot_flags |= ( ACPI_FADT_PSCI_COMPLIANT | >> > ACPI_FADT_PSCI_USE_HVC ); >> > + checksum = acpi_tb_checksum(ACPI_CAST_PTR(u8, fadt), >> > fadt->header.length); >> > + fadt->header.checksum -= checksum; >> > + clean_dcache_va_range(fadt, sizeof(struct acpi_table_fadt)); >> >> Most of this patch is dealing with setting up correctly DOM0 FADT >> although the title doesn't mention it and there is only 2 lines in the >> commit message. This would also need comment in the need explaining what >> this code does. >> >> Furthermore, I don't think this code should live here. The function is >> called by acpi_boot_table_init which should initialize ACPI and not >> trying to modify the ACPI table. >> > i'll split it into two patches with modifying of fadt going into seperate > patch. >> >> We should have a specific dom0 acpi function to modify/add ACPI table >> when it's necessary. >> >> > + return 0; >> > + } >> > + >> > + printk("Unsupported FADT revision %d.%d, should be 5.1+, will >> > disable ACPI\n", >> > + table->revision, fadt->minor_revision); >> > + disable_acpi(); >> > + >> > + return -EINVAL; >> > +} >> > + >> > /* >> > * acpi_boot_table_init() called from setup_arch(), always. >> > * 1. find RSDP and get its address, and then find XSDT >> > @@ -51,6 +82,13 @@ int __init acpi_boot_table_init(void) >> > return error; >> > } >> > >> > + if ( acpi_table_parse(ACPI_SIG_FADT, acpi_parse_fadt) ) >> > + { >> > + /* disable ACPI if no FADT is found */ >> > + disable_acpi(); >> > + printk("Can't find FADT\n"); >> > + } >> > + >> >> I think the code readability will be improved if we introduce >> acpi_get_table_with_size. >> >> Although, this is not implemented by ACPICA but only Linux. Jan may not >> be agree to import it. >> >> > return 0; >> > } >> > >> > diff --git a/xen/arch/arm/acpi/lib.c b/xen/arch/arm/acpi/lib.c >> > index 650beed..fd9bfa4 100644 >> > --- a/xen/arch/arm/acpi/lib.c >> > +++ b/xen/arch/arm/acpi/lib.c >> > @@ -6,3 +6,14 @@ acpi_os_map_iomem(acpi_physical_address phys, acpi_size >> > size) >> > { >> > return __va(phys); >> > } >> >> missing blank line >> >> > +/* 1 to indicate PSCI 0.2+ is implemented */ >> > +inline bool_t acpi_psci_present(void) >> >> inline is not necessary. Although, I would move the function in the >> header because it's very simple. >> >> > +{ >> > + return acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_COMPLIANT; >> > +} >> > + >> > +/* 1 to indicate HVC is present instead of SMC as the PSCI conduit */ >> > +inline bool_t acpi_psci_hvc_present(void) >> >> Ditto. >> >> > +{ >> > + return acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_USE_HVC; >> > +} >> >> Regards, >> >> -- >> -- >> Julien Grall > >