Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752524AbcDKGu3 (ORCPT ); Mon, 11 Apr 2016 02:50:29 -0400 Received: from mx2.suse.de ([195.135.220.15]:59999 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751515AbcDKGuZ (ORCPT ); Mon, 11 Apr 2016 02:50:25 -0400 Subject: Re: [Xen-devel] [PATCH v5 04/14] x86/rtc: replace paravirt rtc check with platform legacy quirk To: "Luis R. Rodriguez" , bp@alien8.de, hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, rusty@rustcorp.com.au References: <1460158825-13117-1-git-send-email-mcgrof@kernel.org> <1460158825-13117-5-git-send-email-mcgrof@kernel.org> Cc: kozerkov@parallels.com, matt@codeblueprint.co.uk, lv.zheng@intel.com, xen-devel@lists.xensource.com, joro@8bytes.org, x86@kernel.org, robert.moore@intel.com, linux-acpi@vger.kernel.org, glin@suse.com, lenb@kernel.org, josh@joshtriplett.org, jlee@suse.com, lguest@lists.ozlabs.org, boris.ostrovsky@oracle.com, andriy.shevchenko@linux.intel.com, toshi.kani@hp.com, andrew.cooper3@citrix.com, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, luto@amacapital.net, david.vrabel@citrix.com, tiwai@suse.de From: Juergen Gross Message-ID: <570B492B.80608@suse.com> Date: Mon, 11 Apr 2016 08:50:19 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.0 MIME-Version: 1.0 In-Reply-To: <1460158825-13117-5-git-send-email-mcgrof@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11575 Lines: 336 On 09/04/16 01:40, Luis R. Rodriguez wrote: > We have 4 types of x86 platforms that disable RTC: > > * Intel MID > * Lguest - uses paravirt > * Xen dom-U - uses paravirt > * x86 on legacy systems annotated with an ACPI legacy flag > > We can consolidate all of these into a platform specific legacy > quirk set early in boot through i386_start_kernel() and through > x86_64_start_reservations(). This deals with the RTC quirks which > we can rely on through the hardware subarch, the ACPI check can > be dealt with separately. > > For Xen things are bit more complex given that the @X86_SUBARCH_XEN > x86_hardware_subarch is shared on for Xen which uses the PV path for > both domU and dom0. Since the semantics for differentiating between > the two are Xen specific we provide a platform helper to help override > default legacy features -- x86_platform.set_legacy_features(). Use > of this helper is highly discouraged, its only purpose should be > to account for the lack of semantics available within your given > x86_hardware_subarch. > > As per 0-day, this bumps the vmlinux size using i386-tinyconfig as > follows: > > TOTAL TEXT init.text x86_early_init_platform_quirks() > +70 +62 +62 +43 > > Only 8 bytes overhead total, as the main increase in size is > all removed via __init. I think this could be even less (see comment below). > > v2: split the subarch check from the ACPI check, clarify > on the ACPI change commit log why ordering works > v3: add x86_platform.set_legacy_features() to account for dom0, > add also size impact on vmlinux as per 0-day report You missed the v5 changes here. > > Suggested-by: Ingo Molnar > Signed-off-by: Luis R. Rodriguez > --- > arch/x86/Makefile | 1 + > arch/x86/include/asm/paravirt.h | 6 ------ > arch/x86/include/asm/paravirt_types.h | 5 ----- > arch/x86/include/asm/processor.h | 1 - > arch/x86/include/asm/x86_init.h | 21 +++++++++++++++++++++ > arch/x86/kernel/Makefile | 6 +++++- > arch/x86/kernel/head32.c | 2 ++ > arch/x86/kernel/head64.c | 1 + > arch/x86/kernel/platform-quirks.c | 21 +++++++++++++++++++++ > arch/x86/kernel/rtc.c | 7 ++----- > arch/x86/lguest/boot.c | 1 - > arch/x86/xen/enlighten.c | 10 +++++++--- > 12 files changed, 60 insertions(+), 22 deletions(-) > create mode 100644 arch/x86/kernel/platform-quirks.c > > diff --git a/arch/x86/Makefile b/arch/x86/Makefile > index 4086abca0b32..f9ed8a7ce2b6 100644 > --- a/arch/x86/Makefile > +++ b/arch/x86/Makefile > @@ -209,6 +209,7 @@ endif > head-y := arch/x86/kernel/head_$(BITS).o > head-y += arch/x86/kernel/head$(BITS).o > head-y += arch/x86/kernel/head.o > +head-y += arch/x86/kernel/platform-quirks.o > > libs-y += arch/x86/lib/ > > diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h > index 601f1b8f9961..6c7a4a192032 100644 > --- a/arch/x86/include/asm/paravirt.h > +++ b/arch/x86/include/asm/paravirt.h > @@ -20,12 +20,6 @@ static inline int paravirt_enabled(void) > return pv_info.paravirt_enabled; > } > > -static inline int paravirt_has_feature(unsigned int feature) > -{ > - WARN_ON_ONCE(!pv_info.paravirt_enabled); > - return (pv_info.features & feature); > -} > - > static inline void load_sp0(struct tss_struct *tss, > struct thread_struct *thread) > { > diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h > index e8c2326478c8..6acc1b26cf40 100644 > --- a/arch/x86/include/asm/paravirt_types.h > +++ b/arch/x86/include/asm/paravirt_types.h > @@ -70,14 +70,9 @@ struct pv_info { > #endif > > int paravirt_enabled; > - unsigned int features; /* valid only if paravirt_enabled is set */ > const char *name; > }; > > -#define paravirt_has(x) paravirt_has_feature(PV_SUPPORTED_##x) > -/* Supported features */ > -#define PV_SUPPORTED_RTC (1<<0) > - > struct pv_init_ops { > /* > * Patch may replace one of the defined code sequences with > diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h > index 9264476f3d57..0c70c7daa6b8 100644 > --- a/arch/x86/include/asm/processor.h > +++ b/arch/x86/include/asm/processor.h > @@ -474,7 +474,6 @@ static inline unsigned long current_top_of_stack(void) > #else > #define __cpuid native_cpuid > #define paravirt_enabled() 0 > -#define paravirt_has(x) 0 > > static inline void load_sp0(struct tss_struct *tss, > struct thread_struct *thread) > diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h > index 1ae89a2721d6..8bb8c1a4615a 100644 > --- a/arch/x86/include/asm/x86_init.h > +++ b/arch/x86/include/asm/x86_init.h > @@ -142,6 +142,15 @@ struct x86_cpuinit_ops { > struct timespec; > > /** > + * struct x86_legacy_features - legacy x86 features > + * > + * @rtc: this device has a CMOS real-time clock present > + */ > +struct x86_legacy_features { > + int rtc; > +}; > + > +/** > * struct x86_platform_ops - platform specific runtime functions > * @calibrate_tsc: calibrate TSC > * @get_wallclock: get time from HW clock like RTC etc. > @@ -152,6 +161,14 @@ struct timespec; > * @save_sched_clock_state: save state for sched_clock() on suspend > * @restore_sched_clock_state: restore state for sched_clock() on resume > * @apic_post_init: adjust apic if neeeded > + * @legacy: legacy features > + * @set_legacy_features: override legacy features. Use of this callback > + * is highly discouraged. You should only need > + * this if your hardware platform requires further > + * custom fine tuning far beyong what may be > + * possible in x86_early_init_platform_quirks() by > + * only using the current x86_hardware_subarch > + * semantics. > */ > struct x86_platform_ops { > unsigned long (*calibrate_tsc)(void); > @@ -165,6 +182,8 @@ struct x86_platform_ops { > void (*save_sched_clock_state)(void); > void (*restore_sched_clock_state)(void); > void (*apic_post_init)(void); > + struct x86_legacy_features legacy; > + void (*set_legacy_features)(void); > }; > > struct pci_dev; > @@ -186,6 +205,8 @@ extern struct x86_cpuinit_ops x86_cpuinit; > extern struct x86_platform_ops x86_platform; > extern struct x86_msi_ops x86_msi; > extern struct x86_io_apic_ops x86_io_apic_ops; > + > +extern void x86_early_init_platform_quirks(void); > extern void x86_init_noop(void); > extern void x86_init_uint_noop(unsigned int unused); > > diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile > index 89f8ade0bc7c..7a9e44d935de 100644 > --- a/arch/x86/kernel/Makefile > +++ b/arch/x86/kernel/Makefile > @@ -2,7 +2,11 @@ > # Makefile for the linux kernel. > # > > -extra-y := head_$(BITS).o head$(BITS).o head.o vmlinux.lds > +extra-y := head_$(BITS).o > +extra-y += head$(BITS).o > +extra-y += head.o > +extra-y += platform-quirks.o > +extra-y += vmlinux.lds > > CPPFLAGS_vmlinux.lds += -U$(UTS_MACHINE) > > diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c > index 2911ef3a9f1c..d784bb547a9d 100644 > --- a/arch/x86/kernel/head32.c > +++ b/arch/x86/kernel/head32.c > @@ -34,6 +34,8 @@ asmlinkage __visible void __init i386_start_kernel(void) > cr4_init_shadow(); > sanitize_boot_params(&boot_params); > > + x86_early_init_platform_quirks(); > + > /* Call the subarch specific early setup function */ > switch (boot_params.hdr.hardware_subarch) { > case X86_SUBARCH_INTEL_MID: > diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c > index 1f4422d5c8d0..b72fb0b71dd1 100644 > --- a/arch/x86/kernel/head64.c > +++ b/arch/x86/kernel/head64.c > @@ -182,6 +182,7 @@ void __init x86_64_start_reservations(char *real_mode_data) > if (!boot_params.hdr.version) > copy_bootdata(__va(real_mode_data)); > > + x86_early_init_platform_quirks(); > reserve_ebda_region(); > > switch (boot_params.hdr.hardware_subarch) { > diff --git a/arch/x86/kernel/platform-quirks.c b/arch/x86/kernel/platform-quirks.c > new file mode 100644 > index 000000000000..021a5f973ce3 > --- /dev/null > +++ b/arch/x86/kernel/platform-quirks.c > @@ -0,0 +1,21 @@ > +#include > +#include > + > +#include > +#include > + > +void __init x86_early_init_platform_quirks(void) > +{ > + x86_platform.legacy.rtc = 1; > + > + switch (boot_params.hdr.hardware_subarch) { > + case X86_SUBARCH_XEN: > + case X86_SUBARCH_LGUEST: > + case X86_SUBARCH_INTEL_MID: > + x86_platform.legacy.rtc = 0; > + break; > + } > + > + if (x86_platform.set_legacy_features) > + x86_platform.set_legacy_features(); > +} > diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c > index 4af8d063fb36..62c48da3889d 100644 > --- a/arch/x86/kernel/rtc.c > +++ b/arch/x86/kernel/rtc.c > @@ -14,6 +14,7 @@ > #include > #include > #include > +#include > > #ifdef CONFIG_X86_32 > /* > @@ -188,10 +189,6 @@ static __init int add_rtc_cmos(void) > if (of_have_populated_dt()) > return 0; > > - /* Intel MID platforms don't have ioport rtc */ > - if (intel_mid_identify_cpu()) > - return -ENODEV; > - > #ifdef CONFIG_ACPI > if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_CMOS_RTC) { > /* This warning can likely go away again in a year or two. */ > @@ -200,7 +197,7 @@ static __init int add_rtc_cmos(void) > } > #endif > > - if (paravirt_enabled() && !paravirt_has(RTC)) > + if (!x86_platform.legacy.rtc) > return -ENODEV; > > platform_device_register(&rtc_device); > diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c > index fd57d3ae7e16..f5497ee5fd2f 100644 > --- a/arch/x86/lguest/boot.c > +++ b/arch/x86/lguest/boot.c > @@ -1414,7 +1414,6 @@ __init void lguest_init(void) > pv_info.kernel_rpl = 1; > /* Everyone except Xen runs with this set. */ > pv_info.shared_kernel_pmd = 1; > - pv_info.features = 0; > > /* > * We set up all the lguest overrides for sensitive operations. These > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c > index 40487f1ecb4c..e066fcf87c3d 100644 > --- a/arch/x86/xen/enlighten.c > +++ b/arch/x86/xen/enlighten.c > @@ -1192,7 +1192,6 @@ static const struct pv_info xen_info __initconst = { > #ifdef CONFIG_X86_64 > .extra_user_64bit_cs = FLAT_USER_CS64, > #endif > - .features = 0, > .name = "Xen", > }; > > @@ -1505,6 +1504,11 @@ static void __init xen_pvh_early_guest_init(void) > } > #endif /* CONFIG_XEN_PVH */ > > +static void xen_dom0_set_legacy_features(void) Can't you make this __init ? > +{ > + x86_platform.legacy.rtc = 1; > +} > + > /* First C function to be called on Xen boot */ > asmlinkage __visible void __init xen_start_kernel(void) > { > @@ -1525,8 +1529,6 @@ asmlinkage __visible void __init xen_start_kernel(void) > > /* Install Xen paravirt ops */ > pv_info = xen_info; > - if (xen_initial_domain()) > - pv_info.features |= PV_SUPPORTED_RTC; > pv_init_ops = xen_init_ops; > if (!xen_pvh_domain()) { > pv_cpu_ops = xen_cpu_ops; > @@ -1679,6 +1681,8 @@ asmlinkage __visible void __init xen_start_kernel(void) > .u.firmware_info.type = XEN_FW_KBD_SHIFT_FLAGS, > }; > > + x86_platform.set_legacy_features = > + xen_dom0_set_legacy_features; > xen_init_vga(info, xen_start_info->console.dom0.info_size); > xen_start_info->console.domU.mfn = 0; > xen_start_info->console.domU.evtchn = 0; > Juergen