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authorLuis R. Rodriguez <mcgrof@kernel.org>2016-04-14 02:04:34 +0200
committerIngo Molnar <mingo@kernel.org>2016-04-22 10:29:01 +0200
commit8d152e7a5c7537b18b4e9e0eb96f549b016636dc (patch)
treede956f52ec790f8ff066dc78c192e3dd8da70a3b /arch/x86/kernel
parenttools/lguest: Make lguest launcher use X86_SUBARCH_LGUEST explicitly (diff)
downloadlinux-8d152e7a5c7537b18b4e9e0eb96f549b016636dc.tar.xz
linux-8d152e7a5c7537b18b4e9e0eb96f549b016636dc.zip
x86/rtc: Replace paravirt rtc check with platform legacy quirk
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. Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> Reviewed-by: Juergen Gross <jgross@suse.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: andrew.cooper3@citrix.com Cc: andriy.shevchenko@linux.intel.com Cc: bigeasy@linutronix.de Cc: boris.ostrovsky@oracle.com Cc: david.vrabel@citrix.com Cc: ffainelli@freebox.fr Cc: george.dunlap@citrix.com Cc: glin@suse.com Cc: jlee@suse.com Cc: josh@joshtriplett.org Cc: julien.grall@linaro.org Cc: konrad.wilk@oracle.com Cc: kozerkov@parallels.com Cc: lenb@kernel.org Cc: lguest@lists.ozlabs.org Cc: linux-acpi@vger.kernel.org Cc: lv.zheng@intel.com Cc: matt@codeblueprint.co.uk Cc: mbizon@freebox.fr Cc: rjw@rjwysocki.net Cc: robert.moore@intel.com Cc: rusty@rustcorp.com.au Cc: tiwai@suse.de Cc: toshi.kani@hp.com Cc: xen-devel@lists.xensource.com Link: http://lkml.kernel.org/r/1460592286-300-5-git-send-email-mcgrof@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/Makefile6
-rw-r--r--arch/x86/kernel/head32.c2
-rw-r--r--arch/x86/kernel/head64.c1
-rw-r--r--arch/x86/kernel/platform-quirks.c21
-rw-r--r--arch/x86/kernel/rtc.c7
5 files changed, 31 insertions, 6 deletions
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 616ebd22ef9a..b81b22ee10ba 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 <linux/kernel.h>
+#include <linux/init.h>
+
+#include <asm/setup.h>
+#include <asm/bios_ebda.h>
+
+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 <asm/time.h>
#include <asm/intel-mid.h>
#include <asm/rtc.h>
+#include <asm/setup.h>
#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);