[PATCH v5 00/14] x86: remove paravirt_enabled()

[PATCH v5 00/14] x86: remove paravirt_enabled()

[Luis R. Rodriguez]

This v5 updates the subarch documentation to annotate that
X86_SUBARCH_XEN can be use for both Xen dom0 and domU, and
adds an optional x86_platform.set_legacy_features() in order
to deal with further platform legacy fine tunings when the
platform requires further semantics than what is currently
available generically, and we've determined we don't need
these semantics added in a generic form to x86. In this case
this was needed for Xen given X86_SUBARCH_XEN can be used for
both dom0 and domU and Xen needs to enable RTC for dom0.

I suspect the hook can possibly later be used for further
fine tunings for HVMLite as it will use X86_SUBARCH_PC, so
its placed towards the end of x86_early_init_platform_quirks()
to enable any platform to take advantage of this.

This also updates the commit logs a bit more to make some
clarifications, and lists the impact of vmlinux size as per
trusty good 'ol 0-day.

The total size impact on vmlinux using i386-tinyconfig:

TOTAL   TEXT   init.text   x86_early_init_platform_quirks()
+136    +125   +125        +96

In total that's only 11 byte overhead, 125 bytes are all .init.text
and that's all freed after boot.

Luis R. Rodriguez (14):
  x86/boot: enumerate documentation for the x86 hardware_subarch
  x86/xen: use X86_SUBARCH_XEN for PV guest boots
  tools/lguest: make lguest launcher use X86_SUBARCH_LGUEST explicitly
  x86/rtc: replace paravirt rtc check with platform legacy quirk
  x86, ACPI: move ACPI_FADT_NO_CMOS_RTC check to ACPI boot code
  x86/init: use a platform legacy quirk for ebda
  tools/lguest: force disable tboot and apm
  apm32: remove paravirt_enabled() use
  x86/tboot: remove paravirt_enabled()
  x86/cpu/intel: remove not needed paravirt_enabled() for f00f work
    around
  pnpbios: replace paravirt_enabled() check with legacy device check
  x86, ACPI: parse ACPI_FADT_LEGACY_DEVICES
  x86/init: rename ebda code file
  x86/paravirt: remove paravirt_enabled()

 arch/x86/Makefile                     |  3 ++-
 arch/x86/include/asm/paravirt.h       | 11 --------
 arch/x86/include/asm/paravirt_types.h |  6 -----
 arch/x86/include/asm/processor.h      |  2 --
 arch/x86/include/asm/x86_init.h       | 50 +++++++++++++++++++++++++++++++++++
 arch/x86/include/uapi/asm/bootparam.h | 37 +++++++++++++++++++++++++-
 arch/x86/kernel/Makefile              |  6 ++++-
 arch/x86/kernel/acpi/boot.c           |  9 +++++++
 arch/x86/kernel/apm_32.c              |  2 +-
 arch/x86/kernel/cpu/intel.c           |  2 +-
 arch/x86/kernel/{head.c => ebda.c}    |  2 +-
 arch/x86/kernel/head32.c              |  2 ++
 arch/x86/kernel/head64.c              |  1 +
 arch/x86/kernel/kvm.c                 |  8 ------
 arch/x86/kernel/paravirt.c            |  1 -
 arch/x86/kernel/platform-quirks.c     | 36 +++++++++++++++++++++++++
 arch/x86/kernel/rtc.c                 | 15 ++---------
 arch/x86/kernel/tboot.c               |  6 -----
 arch/x86/lguest/boot.c                |  3 ---
 arch/x86/xen/enlighten.c              | 12 ++++++---
 drivers/pnp/pnpbios/core.c            |  3 ++-
 include/linux/pnp.h                   |  2 ++
 tools/lguest/lguest.c                 | 10 +++++--
 23 files changed, 166 insertions(+), 63 deletions(-)
 rename arch/x86/kernel/{head.c => ebda.c} (98%)
 create mode 100644 arch/x86/kernel/platform-quirks.c

-- 
2.7.2

[PATCH v5 01/14] x86/boot: enumerate documentation for the x86 hardware_subarch

[Luis R. Rodriguez]

Although hardware_subarch has been in place since the x86 boot
protocol 2.07 it hasn't been used much. Enumerate current possible
values to avoid misuses and help with semantics later at boot
time should this be used further.

These enums should only ever be used by architecture x86 code,
and all that code should be well contained and compartamentalized,
clarify that as well.

v2: updates documentation further -- be a bit more pedantic about
    annotating care and use of these guys.
v3: Use s/SOC/SoC and also anntoate that both domU and dom0 are
    both currently supported through the PV boot path.

Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/include/uapi/asm/bootparam.h | 37 ++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
index 329254373479..bf9fea2f4591 100644
--- a/arch/x86/include/uapi/asm/bootparam.h
+++ b/arch/x86/include/uapi/asm/bootparam.h
@@ -157,7 +157,42 @@ struct boot_params {
 	__u8  _pad9[276];				/* 0xeec */
 } __attribute__((packed));
 
-enum {
+/**
+ * enum x86_hardware_subarch - x86 hardware subarchitecture
+ *
+ * The x86 hardware_subarch and hardware_subarch_data were added as of the x86
+ * boot protocol 2.07 to help distinguish and support custom x86 boot
+ * sequences. This enum represents accepted values for the x86
+ * hardware_subarch.  Custom x86 boot sequences (not X86_SUBARCH_PC) do not
+ * have or simply *cannot* make use of natural stubs like BIOS or EFI, the
+ * hardware_subarch can be used on the Linux entry path to revector to a
+ * subarchitecture stub when needed. This subarchitecture stub can be used to
+ * set up Linux boot parameters or for special care to account for nonstandard
+ * handling of page tables.
+ *
+ * These enums should only ever be used by x86 code, and the code that uses
+ * it should be well contained and compartamentalized.
+ *
+ * KVM and Xen HVM do not have a subarch as these are expected to follow
+ * standard x86 boot entries. If there is a genuine need for "hypervisor" type
+ * that should be considered separately in the future. Future guest types
+ * should seriously consider working with standard x86 boot stubs such as
+ * the BIOS or EFI boot stubs.
+ *
+ * @X86_SUBARCH_PC: Should be used if the hardware is enumerable using standard
+ *	PC mechanisms (PCI, ACPI) and doesn't need a special boot flow.
+ * @X86_SUBARCH_LGUEST: Used for x86 hypervisor demo, lguest
+ * @X86_SUBARCH_XEN: Used for Xen guest types which follow the PV boot path,
+ * 	which start at asm startup_xen() entry point and later jump to the C
+ * 	xen_start_kernel() entry point. Both domU and dom0 type of guests are
+ * 	currently supportd through this PV boot path.
+ * @X86_SUBARCH_INTEL_MID: Used for Intel MID (Mobile Internet Device) platform
+ *	systems which do not have the PCI legacy interfaces.
+ * @X86_SUBARCH_CE4100: Used for Intel CE media processor (CE4100) SoC for
+ * 	for settop boxes and media devices, the use of a subarch for CE4100
+ * 	is more of a hack...
+ */
+enum x86_hardware_subarch {
 	X86_SUBARCH_PC = 0,
 	X86_SUBARCH_LGUEST,
 	X86_SUBARCH_XEN,
-- 
2.7.2

[PATCH v5 02/14] x86/xen: use X86_SUBARCH_XEN for PV guest boots

[Luis R. Rodriguez]

The use of subarch should have no current effect on Xen
PV guests, as such this should have no current functional
effects.

Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/xen/enlighten.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 9b8f1eacc110..40487f1ecb4c 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1661,6 +1661,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
 	boot_params.hdr.ramdisk_image = initrd_start;
 	boot_params.hdr.ramdisk_size = xen_start_info->mod_len;
 	boot_params.hdr.cmd_line_ptr = __pa(xen_start_info->cmd_line);
+	boot_params.hdr.hardware_subarch = X86_SUBARCH_XEN;
 
 	if (!xen_initial_domain()) {
 		add_preferred_console("xenboot", 0, NULL);
-- 
2.7.2

[PATCH v5 03/14] tools/lguest: make lguest launcher use X86_SUBARCH_LGUEST explicitly

[Luis R. Rodriguez]

Be explicit and make use of X86_SUBARCH_LGUEST directly.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 tools/lguest/lguest.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/lguest/lguest.c b/tools/lguest/lguest.c
index 80159e6811c2..ff0aa580c6e1 100644
--- a/tools/lguest/lguest.c
+++ b/tools/lguest/lguest.c
@@ -3351,8 +3351,8 @@ int main(int argc, char *argv[])
 	/* Boot protocol version: 2.07 supports the fields for lguest. */
 	boot->hdr.version = 0x207;
 
-	/* The hardware_subarch value of "1" tells the Guest it's an lguest. */
-	boot->hdr.hardware_subarch = 1;
+	/* X86_SUBARCH_LGUEST tells the Guest it's an lguest. */
+	boot->hdr.hardware_subarch = X86_SUBARCH_LGUEST;
 
 	/* Tell the entry path not to try to reload segment registers. */
 	boot->hdr.loadflags |= KEEP_SEGMENTS;
-- 
2.7.2


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[PATCH v5 04/14] x86/rtc: replace paravirt rtc check with platform legacy quirk

[Luis R. Rodriguez]

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.

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

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 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 <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);
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)
+{
+	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;
-- 
2.7.2

[PATCH v5 05/14] x86, ACPI: move ACPI_FADT_NO_CMOS_RTC check to ACPI boot code

[Luis R. Rodriguez]

This moves the ACPI specific check into the ACPI boot code,
it also takes advantage of the x86_platform.legacy.rtc which
is checked for already on the RTC initialization code. This
lets us remove the nasty #ifdefery and consolidate the checks
to use only one toggle to disable the RTC init code.

The works as RTC is initialized by device_initcall(add_rtc_cmos),
this will run late in boot on start_kernel() during rest_init(),
acpi_parse_fadt() gets called earlier during setup_arch().

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/kernel/acpi/boot.c | 4 ++++
 arch/x86/kernel/rtc.c       | 8 --------
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 8c2f1ef6ca23..8c9c2bdba092 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -913,6 +913,10 @@ late_initcall(hpet_insert_resource);
 
 static int __init acpi_parse_fadt(struct acpi_table_header *table)
 {
+	if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_CMOS_RTC) {
+		pr_debug("ACPI: not registering RTC platform device\n");
+		x86_platform.legacy.rtc = 0;
+	}
 
 #ifdef CONFIG_X86_PM_TIMER
 	/* detect the location of the ACPI PM Timer */
diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
index 62c48da3889d..ff4f4180fefd 100644
--- a/arch/x86/kernel/rtc.c
+++ b/arch/x86/kernel/rtc.c
@@ -189,14 +189,6 @@ static __init int add_rtc_cmos(void)
 	if (of_have_populated_dt())
 		return 0;
 
-#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. */
-		pr_info("ACPI: not registering RTC platform device\n");
-		return -ENODEV;
-	}
-#endif
-
 	if (!x86_platform.legacy.rtc)
 		return -ENODEV;
 
-- 
2.7.2


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[PATCH v5 06/14] x86/init: use a platform legacy quirk for ebda

[Luis R. Rodriguez]

This replaces the paravirt_enabled() check with a
proper x86 legacy platform quirk.

As per 0-day, this bumps the vmlinux size using i386-tinyconfig as
follows:

TOTAL   TEXT   init.text   x86_early_init_platform_quirks()
+39     +35    +35         +25

That's a 4 byte total overhead, the rest is all cleared out
upon init as its all __init text.

v2: document 0-day vmlinux size impact

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/include/asm/x86_init.h   | 3 +++
 arch/x86/kernel/head.c            | 2 +-
 arch/x86/kernel/platform-quirks.c | 4 ++++
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index 8bb8c1a4615a..89d9d57e145d 100644
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -145,9 +145,12 @@ struct timespec;
  * struct x86_legacy_features - legacy x86 features
  *
  * @rtc: this device has a CMOS real-time clock present
+ * @ebda_search: it's safe to search for the EBDA signature in the hardware's
+ * 	low RAM
  */
 struct x86_legacy_features {
 	int rtc;
+	int ebda_search;
 };
 
 /**
diff --git a/arch/x86/kernel/head.c b/arch/x86/kernel/head.c
index 992f442ca155..afe65dffee80 100644
--- a/arch/x86/kernel/head.c
+++ b/arch/x86/kernel/head.c
@@ -38,7 +38,7 @@ void __init reserve_ebda_region(void)
 	 * that the paravirt case can handle memory setup
 	 * correctly, without our help.
 	 */
-	if (paravirt_enabled())
+	if (!x86_platform.legacy.ebda_search)
 		return;
 
 	/* end of low (conventional) memory */
diff --git a/arch/x86/kernel/platform-quirks.c b/arch/x86/kernel/platform-quirks.c
index 021a5f973ce3..01b159781d96 100644
--- a/arch/x86/kernel/platform-quirks.c
+++ b/arch/x86/kernel/platform-quirks.c
@@ -7,8 +7,12 @@
 void __init x86_early_init_platform_quirks(void)
 {
 	x86_platform.legacy.rtc = 1;
+	x86_platform.legacy.ebda_search = 0;
 
 	switch (boot_params.hdr.hardware_subarch) {
+	case X86_SUBARCH_PC:
+		x86_platform.legacy.ebda_search = 1;
+		break;
 	case X86_SUBARCH_XEN:
 	case X86_SUBARCH_LGUEST:
 	case X86_SUBARCH_INTEL_MID:
-- 
2.7.2


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[PATCH v5 07/14] tools/lguest: force disable tboot and apm

[Luis R. Rodriguez]

The paravirt_enabled() check is going away, the area tossed to
the kernel on lguest is not zerored out, so ensure lguest force
disables tboot and apm just in case the kernel file being read might
have this set for whatever reason.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 tools/lguest/lguest.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/lguest/lguest.c b/tools/lguest/lguest.c
index ff0aa580c6e1..0aa75af6e862 100644
--- a/tools/lguest/lguest.c
+++ b/tools/lguest/lguest.c
@@ -3357,6 +3357,12 @@ int main(int argc, char *argv[])
 	/* Tell the entry path not to try to reload segment registers. */
 	boot->hdr.loadflags |= KEEP_SEGMENTS;
 
+	/* We don't support tboot */
+	boot->tboot_addr = 0;
+
+	/* Ensure this is 0 to prevent apm from loading */
+	boot->apm_bios_info.version = 0;
+
 	/* We tell the kernel to initialize the Guest. */
 	tell_kernel(start);
 
-- 
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[PATCH v5 08/14] apm32: remove paravirt_enabled() use

[Luis R. Rodriguez]

There is already a check for apm_info.bios == 0, the
apm_info.bios is set from the boot_params.apm_bios_info.
Both Xen and lguest, which are also the only ones that set
paravirt_enabled to true, never set the apm_bios.info. The

Xen folks are sure force disable to 0 is not needed because
apm_info lives in .bss, we recently forced disabled this on
lguest, and on the Xen side just to be sure Boris zeroed out
the .bss for PV guests through commit 04b6b4a56884327c1648
("xen/x86: Zero out .bss for PV guests"). With this care taken
into consideration the paravirt_enabled() check is simply not
needed anymore.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/kernel/apm_32.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c
index 9307f182fe30..c7364bd633e1 100644
--- a/arch/x86/kernel/apm_32.c
+++ b/arch/x86/kernel/apm_32.c
@@ -2267,7 +2267,7 @@ static int __init apm_init(void)
 
 	dmi_check_system(apm_dmi_table);
 
-	if (apm_info.bios.version == 0 || paravirt_enabled() || machine_is_olpc()) {
+	if (apm_info.bios.version == 0 || machine_is_olpc()) {
 		printk(KERN_INFO "apm: BIOS not found.\n");
 		return -ENODEV;
 	}
-- 
2.7.2


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[PATCH v5 09/14] x86/tboot: remove paravirt_enabled()

[Luis R. Rodriguez]

There is already a check for boot_params.tboot_addr prior
to paravirt_enabled(). Both Xen and lguest, which are also the
only ones that set paravirt_enabled to true, never set the
boot_params.tboot_addr. The Xen folks are sure a force disable
to 0 is not needed, we recently forced disabled this on lguest.
With this in place this check is no longer needed.

Xen folks are sure force disable to 0 is not needed because
apm_info lives in .bss, we recently forced disabled this on
lguest, and on the Xen side just to be sure Boris zeroed out
the .bss for PV guests through commit 04b6b4a56884327c1648
("xen/x86: Zero out .bss for PV guests"). With this care taken
into consideration the paravirt_enabled() check is simply not
needed anymore.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/kernel/tboot.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
index e72a07f20b05..9b0185fbe3eb 100644
--- a/arch/x86/kernel/tboot.c
+++ b/arch/x86/kernel/tboot.c
@@ -74,12 +74,6 @@ void __init tboot_probe(void)
 		return;
 	}
 
-	/* only a natively booted kernel should be using TXT */
-	if (paravirt_enabled()) {
-		pr_warning("non-0 tboot_addr but pv_ops is enabled\n");
-		return;
-	}
-
 	/* Map and check for tboot UUID. */
 	set_fixmap(FIX_TBOOT_BASE, boot_params.tboot_addr);
 	tboot = (struct tboot *)fix_to_virt(FIX_TBOOT_BASE);
-- 
2.7.2


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[PATCH v5 10/14] x86/cpu/intel: remove not needed paravirt_enabled() for f00f work around

[Luis R. Rodriguez]

The X86_BUG_F00F work around is responsible for fixing up the error
generated on attempted F00F exploitation from an OOPS to a SIGILL.
There is no reason why this code should not be allowed to run on
PV guest on a F00F-affected CPU -- it would simply never trigger.
The pv_enabled() check was there only to avoid printing the f00f
workaround, so removing the check is purely a cosmetic change.

Suggested-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/kernel/cpu/intel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index f71a34944b56..66509285ffdd 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -233,7 +233,7 @@ static void intel_workarounds(struct cpuinfo_x86 *c)
 	 * The Quark is also family 5, but does not have the same bug.
 	 */
 	clear_cpu_bug(c, X86_BUG_F00F);
-	if (!paravirt_enabled() && c->x86 == 5 && c->x86_model < 9) {
+	if (c->x86 == 5 && c->x86_model < 9) {
 		static int f00f_workaround_enabled;
 
 		set_cpu_bug(c, X86_BUG_F00F);
-- 
2.7.2


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[PATCH v5 11/14] pnpbios: replace paravirt_enabled() check with legacy device check

[Luis R. Rodriguez]

Since we are removing paravirt_enabled() replace it with a
logical equivalent. Even though PNPBIOS is x86 specific we
add an arch-specific type call, which can be implemented by
any architecture to show how other legacy attribute devices
can later be also checked for with other ACPI legacy attribute
flags.

This implicates the first ACPI 5.2.9.3 IA-PC Boot Architecture
ACPI_FADT_LEGACY_DEVICES flag device, and shows how to add more.

The reason pnpbios gets a defined structure and as such uses
a different approach than the RTC legacy quirk is that ACPI
has a respective RTC flag, while pnpbios does not. We fold
the pnpbios quirk under ACPI_FADT_LEGACY_DEVICES ACPI flag
use case, and use a struct of possible devices to enable
future extensions of this.

As per 0-day, this bumps the vmlinux size using i386-tinyconfig as
follows:

TOTAL   TEXT   init.text   x86_early_init_platform_quirks()
+32     +28    +28         +28

That's 4 byte overhead total, the rest is cleared out on init
as its all __init text.

v2: split out subarch handlng on switch to make it easier
    later to add other subarchs. The 'fall-through' switch
    handling can be confusing and we'll remove it later
    when we add handling for X86_SUBARCH_CE4100.
v3: document vmlinux size impact as per 0-day, and also
    explain why pnpbios is treated differently than the
    RTC legacy feature.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/include/asm/x86_init.h   | 26 ++++++++++++++++++++++++++
 arch/x86/kernel/platform-quirks.c | 11 +++++++++++
 drivers/pnp/pnpbios/core.c        |  3 ++-
 include/linux/pnp.h               |  2 ++
 4 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index 89d9d57e145d..4dcdf74dfed8 100644
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -142,15 +142,41 @@ struct x86_cpuinit_ops {
 struct timespec;
 
 /**
+ * struct x86_legacy_devices - legacy x86 devices
+ *
+ * @pnpbios: this platform can have a PNPBIOS. If this is disabled the platform
+ * 	is known to never have a PNPBIOS.
+ *
+ * These are devices known to require LPC or ISA bus. The definition of legacy
+ * devices adheres to the ACPI 5.2.9.3 IA-PC Boot Architecture flag
+ * ACPI_FADT_LEGACY_DEVICES. These devices consist of user visible devices on
+ * the LPC or ISA bus. User visible devices are devices that have end-user
+ * accessible connectors (for example, LPT parallel port). Legacy devices on
+ * the LPC bus consist for example of serial and parallel ports, PS/2 keyboard
+ * / mouse, and the floppy disk controller. A system that lacks all known
+ * legacy devices can assume all devices can be detected exclusively via
+ * standard device enumeration mechanisms including the ACPI namespace.
+ *
+ * A system which has does not have ACPI_FADT_LEGACY_DEVICES enabled must not
+ * have any of the legacy devices enumerated below present.
+ */
+struct x86_legacy_devices {
+	int pnpbios;
+};
+
+/**
  * struct x86_legacy_features - legacy x86 features
  *
  * @rtc: this device has a CMOS real-time clock present
  * @ebda_search: it's safe to search for the EBDA signature in the hardware's
  * 	low RAM
+ * @devices: legacy x86 devices, refer to struct x86_legacy_devices
+ * 	documentation for further details.
  */
 struct x86_legacy_features {
 	int rtc;
 	int ebda_search;
+	struct x86_legacy_devices devices;
 };
 
 /**
diff --git a/arch/x86/kernel/platform-quirks.c b/arch/x86/kernel/platform-quirks.c
index 01b159781d96..ab643825a7aa 100644
--- a/arch/x86/kernel/platform-quirks.c
+++ b/arch/x86/kernel/platform-quirks.c
@@ -8,6 +8,7 @@ void __init x86_early_init_platform_quirks(void)
 {
 	x86_platform.legacy.rtc = 1;
 	x86_platform.legacy.ebda_search = 0;
+	x86_platform.legacy.devices.pnpbios = 1;
 
 	switch (boot_params.hdr.hardware_subarch) {
 	case X86_SUBARCH_PC:
@@ -15,6 +16,9 @@ void __init x86_early_init_platform_quirks(void)
 		break;
 	case X86_SUBARCH_XEN:
 	case X86_SUBARCH_LGUEST:
+		x86_platform.legacy.devices.pnpbios = 0;
+		x86_platform.legacy.rtc = 0;
+		break;
 	case X86_SUBARCH_INTEL_MID:
 		x86_platform.legacy.rtc = 0;
 		break;
@@ -23,3 +27,10 @@ void __init x86_early_init_platform_quirks(void)
 	if (x86_platform.set_legacy_features)
 		x86_platform.set_legacy_features();
 }
+
+#if defined(CONFIG_PNPBIOS)
+bool __init arch_pnpbios_disabled(void)
+{
+	return x86_platform.legacy.devices.pnpbios == 0;
+}
+#endif
diff --git a/drivers/pnp/pnpbios/core.c b/drivers/pnp/pnpbios/core.c
index facd43b8516c..81603d99082b 100644
--- a/drivers/pnp/pnpbios/core.c
+++ b/drivers/pnp/pnpbios/core.c
@@ -521,10 +521,11 @@ static int __init pnpbios_init(void)
 	int ret;
 
 	if (pnpbios_disabled || dmi_check_system(pnpbios_dmi_table) ||
-	    paravirt_enabled()) {
+	    arch_pnpbios_disabled()) {
 		printk(KERN_INFO "PnPBIOS: Disabled\n");
 		return -ENODEV;
 	}
+
 #ifdef CONFIG_PNPACPI
 	if (!acpi_disabled && !pnpacpi_disabled) {
 		pnpbios_disabled = 1;
diff --git a/include/linux/pnp.h b/include/linux/pnp.h
index 5df733b8f704..2588ca6a9028 100644
--- a/include/linux/pnp.h
+++ b/include/linux/pnp.h
@@ -337,9 +337,11 @@ extern struct mutex pnp_res_mutex;
 
 #ifdef CONFIG_PNPBIOS
 extern struct pnp_protocol pnpbios_protocol;
+extern bool arch_pnpbios_disabled(void);
 #define pnp_device_is_pnpbios(dev) ((dev)->protocol == (&pnpbios_protocol))
 #else
 #define pnp_device_is_pnpbios(dev) 0
+#define arch_pnpbios_disabled()	false
 #endif
 
 #ifdef CONFIG_PNPACPI
-- 
2.7.2


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[PATCH v5 12/14] x86, ACPI: parse ACPI_FADT_LEGACY_DEVICES

[Luis R. Rodriguez]

ACPI 5.2.9.3 IA-PC Boot Architecture flag ACPI_FADT_LEGACY_DEVICES
can be used to determine if a system has legacy devices LPC or
ISA devices. The x86 platform already has a struct which lists
known associated legacy devices, we start off careful only
by disabling root devices we should not regress with. The struct
and device list can be expanded with time to cover more root
legacy components.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/kernel/acpi/boot.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 8c9c2bdba092..c9a06e573fa5 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -913,6 +913,11 @@ late_initcall(hpet_insert_resource);
 
 static int __init acpi_parse_fadt(struct acpi_table_header *table)
 {
+	if (!(acpi_gbl_FADT.boot_flags & ACPI_FADT_LEGACY_DEVICES)) {
+		pr_debug("ACPI: no legacy devices present\n");
+		x86_platform.legacy.devices.pnpbios = 0;
+	}
+
 	if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_CMOS_RTC) {
 		pr_debug("ACPI: not registering RTC platform device\n");
 		x86_platform.legacy.rtc = 0;
-- 
2.7.2

[PATCH v5 13/14] x86/init: rename ebda code file

[Luis R. Rodriguez]

This makes it clearer what this is.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/Makefile                  | 2 +-
 arch/x86/kernel/Makefile           | 2 +-
 arch/x86/kernel/{head.c => ebda.c} | 0
 3 files changed, 2 insertions(+), 2 deletions(-)
 rename arch/x86/kernel/{head.c => ebda.c} (100%)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index f9ed8a7ce2b6..6fce7f096b88 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -208,7 +208,7 @@ 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/ebda.o
 head-y += arch/x86/kernel/platform-quirks.o
 
 libs-y  += arch/x86/lib/
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 7a9e44d935de..0503f5bfb18d 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -4,7 +4,7 @@
 
 extra-y	:= head_$(BITS).o
 extra-y	+= head$(BITS).o
-extra-y	+= head.o
+extra-y	+= ebda.o
 extra-y	+= platform-quirks.o
 extra-y	+= vmlinux.lds
 
diff --git a/arch/x86/kernel/head.c b/arch/x86/kernel/ebda.c
similarity index 100%
rename from arch/x86/kernel/head.c
rename to arch/x86/kernel/ebda.c
-- 
2.7.2

[PATCH v5 14/14] x86/paravirt: remove paravirt_enabled()

[Luis R. Rodriguez]

That that paravirt_enabled() is replaced with proper
x86 semantics we can remove it.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/include/asm/paravirt.h       | 5 -----
 arch/x86/include/asm/paravirt_types.h | 1 -
 arch/x86/include/asm/processor.h      | 1 -
 arch/x86/kernel/kvm.c                 | 8 --------
 arch/x86/kernel/paravirt.c            | 1 -
 arch/x86/lguest/boot.c                | 2 --
 arch/x86/xen/enlighten.c              | 1 -
 7 files changed, 19 deletions(-)

diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 6c7a4a192032..dff26bc91b17 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -15,11 +15,6 @@
 #include <linux/cpumask.h>
 #include <asm/frame.h>
 
-static inline int paravirt_enabled(void)
-{
-	return pv_info.paravirt_enabled;
-}
-
 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 6acc1b26cf40..7fedf24bd811 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -69,7 +69,6 @@ struct pv_info {
 	u16 extra_user_64bit_cs;  /* __USER_CS if none */
 #endif
 
-	int paravirt_enabled;
 	const char *name;
 };
 
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 0c70c7daa6b8..8d326e822cb8 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -473,7 +473,6 @@ static inline unsigned long current_top_of_stack(void)
 #include <asm/paravirt.h>
 #else
 #define __cpuid			native_cpuid
-#define paravirt_enabled()	0
 
 static inline void load_sp0(struct tss_struct *tss,
 			    struct thread_struct *thread)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index dc1207e2f193..eea2a6f72b31 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -285,14 +285,6 @@ static void __init paravirt_ops_setup(void)
 {
 	pv_info.name = "KVM";
 
-	/*
-	 * KVM isn't paravirt in the sense of paravirt_enabled.  A KVM
-	 * guest kernel works like a bare metal kernel with additional
-	 * features, and paravirt_enabled is about features that are
-	 * missing.
-	 */
-	pv_info.paravirt_enabled = 0;
-
 	if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
 		pv_cpu_ops.io_delay = kvm_io_delay;
 
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index f08ac28b8136..71a2d8a05a66 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -294,7 +294,6 @@ enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
 
 struct pv_info pv_info = {
 	.name = "bare hardware",
-	.paravirt_enabled = 0,
 	.kernel_rpl = 0,
 	.shared_kernel_pmd = 1,	/* Only used when CONFIG_X86_PAE is set */
 
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index f5497ee5fd2f..3847e736702e 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -1408,8 +1408,6 @@ __init void lguest_init(void)
 {
 	/* We're under lguest. */
 	pv_info.name = "lguest";
-	/* Paravirt is enabled. */
-	pv_info.paravirt_enabled = 1;
 	/* We're running at privilege level 1, not 0 as normal. */
 	pv_info.kernel_rpl = 1;
 	/* Everyone except Xen runs with this set. */
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index e066fcf87c3d..7c1da39623f4 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1186,7 +1186,6 @@ static unsigned xen_patch(u8 type, u16 clobbers, void *insnbuf,
 }
 
 static const struct pv_info xen_info __initconst = {
-	.paravirt_enabled = 1,
 	.shared_kernel_pmd = 0,
 
 #ifdef CONFIG_X86_64
-- 
2.7.2

[PATCH v5 02/14] x86/xen: use X86_SUBARCH_XEN for PV guest boots

[Luis R. Rodriguez]

The use of subarch should have no current effect on Xen
PV guests, as such this should have no current functional
effects.

Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/xen/enlighten.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 9b8f1eacc110..40487f1ecb4c 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1661,6 +1661,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
 	boot_params.hdr.ramdisk_image = initrd_start;
 	boot_params.hdr.ramdisk_size = xen_start_info->mod_len;
 	boot_params.hdr.cmd_line_ptr = __pa(xen_start_info->cmd_line);
+	boot_params.hdr.hardware_subarch = X86_SUBARCH_XEN;
 
 	if (!xen_initial_domain()) {
 		add_preferred_console("xenboot", 0, NULL);
-- 
2.7.2

[PATCH v5 04/14] x86/rtc: replace paravirt rtc check with platform legacy quirk

[Luis R. Rodriguez]

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.

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

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 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 <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);
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)
+{
+	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;
-- 
2.7.2

[PATCH v5 05/14] x86, ACPI: move ACPI_FADT_NO_CMOS_RTC check to ACPI boot code

[Luis R. Rodriguez]

This moves the ACPI specific check into the ACPI boot code,
it also takes advantage of the x86_platform.legacy.rtc which
is checked for already on the RTC initialization code. This
lets us remove the nasty #ifdefery and consolidate the checks
to use only one toggle to disable the RTC init code.

The works as RTC is initialized by device_initcall(add_rtc_cmos),
this will run late in boot on start_kernel() during rest_init(),
acpi_parse_fadt() gets called earlier during setup_arch().

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/kernel/acpi/boot.c | 4 ++++
 arch/x86/kernel/rtc.c       | 8 --------
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 8c2f1ef6ca23..8c9c2bdba092 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -913,6 +913,10 @@ late_initcall(hpet_insert_resource);
 
 static int __init acpi_parse_fadt(struct acpi_table_header *table)
 {
+	if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_CMOS_RTC) {
+		pr_debug("ACPI: not registering RTC platform device\n");
+		x86_platform.legacy.rtc = 0;
+	}
 
 #ifdef CONFIG_X86_PM_TIMER
 	/* detect the location of the ACPI PM Timer */
diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
index 62c48da3889d..ff4f4180fefd 100644
--- a/arch/x86/kernel/rtc.c
+++ b/arch/x86/kernel/rtc.c
@@ -189,14 +189,6 @@ static __init int add_rtc_cmos(void)
 	if (of_have_populated_dt())
 		return 0;
 
-#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. */
-		pr_info("ACPI: not registering RTC platform device\n");
-		return -ENODEV;
-	}
-#endif
-
 	if (!x86_platform.legacy.rtc)
 		return -ENODEV;
 
-- 
2.7.2

[PATCH v5 07/14] tools/lguest: force disable tboot and apm

[Luis R. Rodriguez]

The paravirt_enabled() check is going away, the area tossed to
the kernel on lguest is not zerored out, so ensure lguest force
disables tboot and apm just in case the kernel file being read might
have this set for whatever reason.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 tools/lguest/lguest.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/lguest/lguest.c b/tools/lguest/lguest.c
index ff0aa580c6e1..0aa75af6e862 100644
--- a/tools/lguest/lguest.c
+++ b/tools/lguest/lguest.c
@@ -3357,6 +3357,12 @@ int main(int argc, char *argv[])
 	/* Tell the entry path not to try to reload segment registers. */
 	boot->hdr.loadflags |= KEEP_SEGMENTS;
 
+	/* We don't support tboot */
+	boot->tboot_addr = 0;
+
+	/* Ensure this is 0 to prevent apm from loading */
+	boot->apm_bios_info.version = 0;
+
 	/* We tell the kernel to initialize the Guest. */
 	tell_kernel(start);
 
-- 
2.7.2

[PATCH v5 09/14] x86/tboot: remove paravirt_enabled()

[Luis R. Rodriguez]

There is already a check for boot_params.tboot_addr prior
to paravirt_enabled(). Both Xen and lguest, which are also the
only ones that set paravirt_enabled to true, never set the
boot_params.tboot_addr. The Xen folks are sure a force disable
to 0 is not needed, we recently forced disabled this on lguest.
With this in place this check is no longer needed.

Xen folks are sure force disable to 0 is not needed because
apm_info lives in .bss, we recently forced disabled this on
lguest, and on the Xen side just to be sure Boris zeroed out
the .bss for PV guests through commit 04b6b4a56884327c1648
("xen/x86: Zero out .bss for PV guests"). With this care taken
into consideration the paravirt_enabled() check is simply not
needed anymore.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/kernel/tboot.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
index e72a07f20b05..9b0185fbe3eb 100644
--- a/arch/x86/kernel/tboot.c
+++ b/arch/x86/kernel/tboot.c
@@ -74,12 +74,6 @@ void __init tboot_probe(void)
 		return;
 	}
 
-	/* only a natively booted kernel should be using TXT */
-	if (paravirt_enabled()) {
-		pr_warning("non-0 tboot_addr but pv_ops is enabled\n");
-		return;
-	}
-
 	/* Map and check for tboot UUID. */
 	set_fixmap(FIX_TBOOT_BASE, boot_params.tboot_addr);
 	tboot = (struct tboot *)fix_to_virt(FIX_TBOOT_BASE);
-- 
2.7.2

[PATCH v5 10/14] x86/cpu/intel: remove not needed paravirt_enabled() for f00f work around

[Luis R. Rodriguez]

The X86_BUG_F00F work around is responsible for fixing up the error
generated on attempted F00F exploitation from an OOPS to a SIGILL.
There is no reason why this code should not be allowed to run on
PV guest on a F00F-affected CPU -- it would simply never trigger.
The pv_enabled() check was there only to avoid printing the f00f
workaround, so removing the check is purely a cosmetic change.

Suggested-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/kernel/cpu/intel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index f71a34944b56..66509285ffdd 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -233,7 +233,7 @@ static void intel_workarounds(struct cpuinfo_x86 *c)
 	 * The Quark is also family 5, but does not have the same bug.
 	 */
 	clear_cpu_bug(c, X86_BUG_F00F);
-	if (!paravirt_enabled() && c->x86 == 5 && c->x86_model < 9) {
+	if (c->x86 == 5 && c->x86_model < 9) {
 		static int f00f_workaround_enabled;
 
 		set_cpu_bug(c, X86_BUG_F00F);
-- 
2.7.2

[PATCH v5 14/14] x86/paravirt: remove paravirt_enabled()

[Luis R. Rodriguez]

That that paravirt_enabled() is replaced with proper
x86 semantics we can remove it.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/include/asm/paravirt.h       | 5 -----
 arch/x86/include/asm/paravirt_types.h | 1 -
 arch/x86/include/asm/processor.h      | 1 -
 arch/x86/kernel/kvm.c                 | 8 --------
 arch/x86/kernel/paravirt.c            | 1 -
 arch/x86/lguest/boot.c                | 2 --
 arch/x86/xen/enlighten.c              | 1 -
 7 files changed, 19 deletions(-)

diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 6c7a4a192032..dff26bc91b17 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -15,11 +15,6 @@
 #include <linux/cpumask.h>
 #include <asm/frame.h>
 
-static inline int paravirt_enabled(void)
-{
-	return pv_info.paravirt_enabled;
-}
-
 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 6acc1b26cf40..7fedf24bd811 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -69,7 +69,6 @@ struct pv_info {
 	u16 extra_user_64bit_cs;  /* __USER_CS if none */
 #endif
 
-	int paravirt_enabled;
 	const char *name;
 };
 
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 0c70c7daa6b8..8d326e822cb8 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -473,7 +473,6 @@ static inline unsigned long current_top_of_stack(void)
 #include <asm/paravirt.h>
 #else
 #define __cpuid			native_cpuid
-#define paravirt_enabled()	0
 
 static inline void load_sp0(struct tss_struct *tss,
 			    struct thread_struct *thread)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index dc1207e2f193..eea2a6f72b31 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -285,14 +285,6 @@ static void __init paravirt_ops_setup(void)
 {
 	pv_info.name = "KVM";
 
-	/*
-	 * KVM isn't paravirt in the sense of paravirt_enabled.  A KVM
-	 * guest kernel works like a bare metal kernel with additional
-	 * features, and paravirt_enabled is about features that are
-	 * missing.
-	 */
-	pv_info.paravirt_enabled = 0;
-
 	if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
 		pv_cpu_ops.io_delay = kvm_io_delay;
 
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index f08ac28b8136..71a2d8a05a66 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -294,7 +294,6 @@ enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
 
 struct pv_info pv_info = {
 	.name = "bare hardware",
-	.paravirt_enabled = 0,
 	.kernel_rpl = 0,
 	.shared_kernel_pmd = 1,	/* Only used when CONFIG_X86_PAE is set */
 
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index f5497ee5fd2f..3847e736702e 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -1408,8 +1408,6 @@ __init void lguest_init(void)
 {
 	/* We're under lguest. */
 	pv_info.name = "lguest";
-	/* Paravirt is enabled. */
-	pv_info.paravirt_enabled = 1;
 	/* We're running at privilege level 1, not 0 as normal. */
 	pv_info.kernel_rpl = 1;
 	/* Everyone except Xen runs with this set. */
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index e066fcf87c3d..7c1da39623f4 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1186,7 +1186,6 @@ static unsigned xen_patch(u8 type, u16 clobbers, void *insnbuf,
 }
 
 static const struct pv_info xen_info __initconst = {
-	.paravirt_enabled = 1,
 	.shared_kernel_pmd = 0,
 
 #ifdef CONFIG_X86_64
-- 
2.7.2

Re: [PATCH v5 00/14] x86: remove paravirt_enabled()

[Luis R. Rodriguez]

BTW also here's a tree if someone needs it:

https://git.kernel.org/cgit/linux/kernel/git/mcgrof/linux-next.git/log/?h=20160408-pv-disabled-v5

  Luis

Re: [Xen-devel] [PATCH v5 04/14] x86/rtc: replace paravirt rtc check with platform legacy quirk

[Juergen Gross]

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 <mingo@kernel.org>
> Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
> ---
>  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 <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);
> 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

Re: [Xen-devel] [PATCH v5 14/14] x86/paravirt: remove paravirt_enabled()

[Juergen Gross]

On 09/04/16 01:40, Luis R. Rodriguez wrote:
> That that paravirt_enabled() is replaced with proper
> x86 semantics we can remove it.
> 
> Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
> ---
>  arch/x86/include/asm/paravirt.h       | 5 -----
>  arch/x86/include/asm/paravirt_types.h | 1 -
>  arch/x86/include/asm/processor.h      | 1 -
>  arch/x86/kernel/kvm.c                 | 8 --------
>  arch/x86/kernel/paravirt.c            | 1 -
>  arch/x86/lguest/boot.c                | 2 --
>  arch/x86/xen/enlighten.c              | 1 -
>  7 files changed, 19 deletions(-)

Xen parts:

Acked-by: Juergen Gross <jgross@suse.com>


Juergen

> 
> diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
> index 6c7a4a192032..dff26bc91b17 100644
> --- a/arch/x86/include/asm/paravirt.h
> +++ b/arch/x86/include/asm/paravirt.h
> @@ -15,11 +15,6 @@
>  #include <linux/cpumask.h>
>  #include <asm/frame.h>
>  
> -static inline int paravirt_enabled(void)
> -{
> -	return pv_info.paravirt_enabled;
> -}
> -
>  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 6acc1b26cf40..7fedf24bd811 100644
> --- a/arch/x86/include/asm/paravirt_types.h
> +++ b/arch/x86/include/asm/paravirt_types.h
> @@ -69,7 +69,6 @@ struct pv_info {
>  	u16 extra_user_64bit_cs;  /* __USER_CS if none */
>  #endif
>  
> -	int paravirt_enabled;
>  	const char *name;
>  };
>  
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 0c70c7daa6b8..8d326e822cb8 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -473,7 +473,6 @@ static inline unsigned long current_top_of_stack(void)
>  #include <asm/paravirt.h>
>  #else
>  #define __cpuid			native_cpuid
> -#define paravirt_enabled()	0
>  
>  static inline void load_sp0(struct tss_struct *tss,
>  			    struct thread_struct *thread)
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index dc1207e2f193..eea2a6f72b31 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -285,14 +285,6 @@ static void __init paravirt_ops_setup(void)
>  {
>  	pv_info.name = "KVM";
>  
> -	/*
> -	 * KVM isn't paravirt in the sense of paravirt_enabled.  A KVM
> -	 * guest kernel works like a bare metal kernel with additional
> -	 * features, and paravirt_enabled is about features that are
> -	 * missing.
> -	 */
> -	pv_info.paravirt_enabled = 0;
> -
>  	if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
>  		pv_cpu_ops.io_delay = kvm_io_delay;
>  
> diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
> index f08ac28b8136..71a2d8a05a66 100644
> --- a/arch/x86/kernel/paravirt.c
> +++ b/arch/x86/kernel/paravirt.c
> @@ -294,7 +294,6 @@ enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
>  
>  struct pv_info pv_info = {
>  	.name = "bare hardware",
> -	.paravirt_enabled = 0,
>  	.kernel_rpl = 0,
>  	.shared_kernel_pmd = 1,	/* Only used when CONFIG_X86_PAE is set */
>  
> diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
> index f5497ee5fd2f..3847e736702e 100644
> --- a/arch/x86/lguest/boot.c
> +++ b/arch/x86/lguest/boot.c
> @@ -1408,8 +1408,6 @@ __init void lguest_init(void)
>  {
>  	/* We're under lguest. */
>  	pv_info.name = "lguest";
> -	/* Paravirt is enabled. */
> -	pv_info.paravirt_enabled = 1;
>  	/* We're running at privilege level 1, not 0 as normal. */
>  	pv_info.kernel_rpl = 1;
>  	/* Everyone except Xen runs with this set. */
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index e066fcf87c3d..7c1da39623f4 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1186,7 +1186,6 @@ static unsigned xen_patch(u8 type, u16 clobbers, void *insnbuf,
>  }
>  
>  static const struct pv_info xen_info __initconst = {
> -	.paravirt_enabled = 1,
>  	.shared_kernel_pmd = 0,
>  
>  #ifdef CONFIG_X86_64
> 

Re: [PATCH v5 04/14] x86/rtc: replace paravirt rtc check with platform legacy quirk

[Boris Ostrovsky]

On 04/08/2016 07:40 PM, Luis R. Rodriguez wrote:

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;


I don't think this belongs here --- we are in the ops structure.

-boris

> +	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);
>   
>


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Re: [Xen-devel] [PATCH v5 04/14] x86/rtc: replace paravirt rtc check with platform legacy quirk

[Luis R. Rodriguez]

On Mon, Apr 11, 2016 at 08:50:19AM +0200, Juergen Gross wrote:
> 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).

Indeed.

> 
> > 
> > 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.


Sorry this was a mismatch, the v3 notes are the v5 notes, the
discrepancy between this and the subject was that the patches
have changed over time to be split out on their own and so 
iterations have been meshed / split, etc.. I'll just
update the accounting to match the subject next.

In next replies it would really help if you trim your review on
patches by removing context of the e-mail for hunks / file without
feedback, and only keep the file name / hunk for which you are
commenting on.

For instance:

> > 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 ?

Indeed, will change.

  Luis

Re: [PATCH v5 04/14] x86/rtc: replace paravirt rtc check with platform legacy quirk

[Luis R. Rodriguez]

On Mon, Apr 11, 2016 at 09:49:56AM -0400, Boris Ostrovsky wrote:
> On 04/08/2016 07:40 PM, Luis R. Rodriguez wrote:
> 
> 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;
> 
> 
> I don't think this belongs here --- we are in the ops structure.

Bike shed thing -- I went with what Ingo suggested [0], which was to
embed things under x86_platform, and that happens to be this struct.

So unless I hear otherwise from the maintainer I'm sticking with it.

http://lkml.kernel.org/r/20160224083259.GA20579@gmail.com

  Luis

Re: [PATCH v5 01/14] x86/boot: enumerate documentation for the x86 hardware_subarch

[Ingo Molnar]

* Luis R. Rodriguez <mcgrof@kernel.org> wrote:

> Although hardware_subarch has been in place since the x86 boot
> protocol 2.07 it hasn't been used much. Enumerate current possible
> values to avoid misuses and help with semantics later at boot
> time should this be used further.
> 
> These enums should only ever be used by architecture x86 code,
> and all that code should be well contained and compartamentalized,
> clarify that as well.
> 
> v2: updates documentation further -- be a bit more pedantic about
>     annotating care and use of these guys.
> v3: Use s/SOC/SoC and also anntoate that both domU and dom0 are
>     both currently supported through the PV boot path.
> 
> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
> ---
>  arch/x86/include/uapi/asm/bootparam.h | 37 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 36 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
> index 329254373479..bf9fea2f4591 100644
> --- a/arch/x86/include/uapi/asm/bootparam.h
> +++ b/arch/x86/include/uapi/asm/bootparam.h
> @@ -157,7 +157,42 @@ struct boot_params {
>  	__u8  _pad9[276];				/* 0xeec */
>  } __attribute__((packed));
>  
> -enum {
> +/**
> + * enum x86_hardware_subarch - x86 hardware subarchitecture

Could you add some prominent warning here, like:

> + * WARNING: the 'x86 subarch flag' is only used for legacy hacks, for platform
> + *          features that are not easily enumerated or discoverable. You should
> + *          not ever use this for new features.

Thanks,

	Ingo

Re: [PATCH v5 07/14] tools/lguest: force disable tboot and apm

[Ingo Molnar]

* Luis R. Rodriguez <mcgrof@kernel.org> wrote:

> The paravirt_enabled() check is going away, the area tossed to
> the kernel on lguest is not zerored out, so ensure lguest force
> disables tboot and apm just in case the kernel file being read might
> have this set for whatever reason.
> 
> Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
> ---
>  tools/lguest/lguest.c | 6 ++++++
>  1 file changed, 6 insertions(+)

Yeah, so the v4 patch was acked by Rusty:

  Acked-by: Rusty Russell <rusty@rustcorp.com.au>

... but you didn't add his ack to the v5 patch :-(

Please don't do this! Also please double check all past replies to make sure no 
acks got lost. I noticed this one, but there might be more.

Thanks,

	Ingo

Re: [PATCH v5 01/14] x86/boot: enumerate documentation for the x86 hardware_subarch

[Luis R. Rodriguez]

On Wed, Apr 13, 2016 at 10:01:32AM +0200, Ingo Molnar wrote:
> > diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
> > index 329254373479..bf9fea2f4591 100644
> > --- a/arch/x86/include/uapi/asm/bootparam.h
> > +++ b/arch/x86/include/uapi/asm/bootparam.h
> > @@ -157,7 +157,42 @@ struct boot_params {
> >  	__u8  _pad9[276];				/* 0xeec */
> >  } __attribute__((packed));
> >  
> > -enum {
> > +/**
> > + * enum x86_hardware_subarch - x86 hardware subarchitecture
> 
> Could you add some prominent warning here, like:
> 
> > + * WARNING: the 'x86 subarch flag' is only used for legacy hacks, for platform
> > + *          features that are not easily enumerated or discoverable. You should
> > + *          not ever use this for new features.

With pleasure, added.

  Luis

Re: [PATCH v5 07/14] tools/lguest: force disable tboot and apm

[Luis R. Rodriguez]

On Wed, Apr 13, 2016 at 10:44:46AM +0200, Ingo Molnar wrote:
> 
> * Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> 
> > The paravirt_enabled() check is going away, the area tossed to
> > the kernel on lguest is not zerored out, so ensure lguest force
> > disables tboot and apm just in case the kernel file being read might
> > have this set for whatever reason.
> > 
> > Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
> > ---
> >  tools/lguest/lguest.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> 
> Yeah, so the v4 patch was acked by Rusty:
> 
>   Acked-by: Rusty Russell <rusty@rustcorp.com.au>
> 
> ... but you didn't add his ack to the v5 patch :-(

Sorry about that. Added.

> Please don't do this! Also please double check all past replies to make sure no 
> acks got lost. I noticed this one, but there might be more.

I thought I had only left out the Acks for patches I later modified
significantly. Sorry. Will revise.

  Luis

Re: [Xen-devel] [PATCH v5 04/14] x86/rtc: replace paravirt rtc check with platform legacy quirk

[Luis R. Rodriguez]

On Tue, Apr 12, 2016 at 10:50:56PM +0200, Luis R. Rodriguez wrote:
> On Mon, Apr 11, 2016 at 08:50:19AM +0200, Juergen Gross wrote:
> > On 09/04/16 01:40, Luis R. Rodriguez wrote:
> > > 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 

> > > +static void xen_dom0_set_legacy_features(void)
> > 
> > Can't you make this __init ?
> 
> Indeed, will change.

0-day tests indicates no size gains, that might be a build cache
issue not sure. Either way, will fold the __init change into
a v6.

  Luis