[PATCH v2 0/9] xen/x86: PVH Dom0 fixes and fallout adjustments

[PATCH v2 0/9] xen/x86: PVH Dom0 fixes and fallout adjustments

[Jan Beulich]

In order to try to debug hypervisor side breakage from XSA-378 I found
myself urged to finally give PVH Dom0 a try. Sadly things didn't work
quite as expected. In the course of investigating these issues I actually
spotted one piece of PV Dom0 breakage as well, a fix for which is also
included here.

There are one immediate remaining issues: Dom0, unlike in the PV case,
cannot access the screen (to use as a console) when in a non-default
mode (i.e. not 80x25 text), as the necessary information (in particular
about VESA-bases LFB modes) is not communicated. On the hypervisor side
this looks like deliberate behavior, but it is unclear to me what the
intentions were towards an alternative model. (X may be able to access
the screen depending on whether it has a suitable driver besides the
presently unusable /dev/fb<N> based one.)

v2 merely addresses small review comments in patches 7 and 9 (see there).

1: xen/x86: prevent PVH type from getting clobbered
2: xen/x86: allow PVH Dom0 without XEN_PV=y
3: xen/x86: make "earlyprintk=xen" work better for PVH Dom0
4: xen/x86: allow "earlyprintk=xen" to work for PV Dom0
5: xen/x86: make "earlyprintk=xen" work for HVM/PVH DomU
6: xen/x86: generalize preferred console model from PV to PVH Dom0
7: xen/x86: hook up xen_banner() also for PVH 
8: x86/PVH: adjust function/data placement
9: xen/x86: adjust data placement

Jan

[PATCH v2 1/9] xen/x86: prevent PVH type from getting clobbered

[Jan Beulich]

Like xen_start_flags, xen_domain_type gets set before .bss gets cleared.
Hence this variable also needs to be prevented from getting put in .bss,
which is possible because XEN_NATIVE is an enumerator evaluating to
zero. Any use prior to init_hvm_pv_info() setting the variable again
would lead to wrong decisions; one such case is xenboot_console_setup()
when called as a result of "earlyprintk=xen".

Use __ro_after_init as more applicable than either __section(".data") or
__read_mostly.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>

--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -52,9 +52,6 @@ DEFINE_PER_CPU(struct vcpu_info, xen_vcp
 DEFINE_PER_CPU(uint32_t, xen_vcpu_id);
 EXPORT_PER_CPU_SYMBOL(xen_vcpu_id);
 
-enum xen_domain_type xen_domain_type = XEN_NATIVE;
-EXPORT_SYMBOL_GPL(xen_domain_type);
-
 unsigned long *machine_to_phys_mapping = (void *)MACH2PHYS_VIRT_START;
 EXPORT_SYMBOL(machine_to_phys_mapping);
 unsigned long  machine_to_phys_nr;
@@ -69,9 +66,11 @@ __read_mostly int xen_have_vector_callba
 EXPORT_SYMBOL_GPL(xen_have_vector_callback);
 
 /*
- * NB: needs to live in .data because it's used by xen_prepare_pvh which runs
- * before clearing the bss.
+ * NB: These need to live in .data or alike because they're used by
+ * xen_prepare_pvh() which runs before clearing the bss.
  */
+enum xen_domain_type __ro_after_init xen_domain_type = XEN_NATIVE;
+EXPORT_SYMBOL_GPL(xen_domain_type);
 uint32_t xen_start_flags __section(".data") = 0;
 EXPORT_SYMBOL(xen_start_flags);
 

[PATCH v2 2/9] xen/x86: allow PVH Dom0 without XEN_PV=y

[Jan Beulich]

Decouple XEN_DOM0 from XEN_PV, converting some existing uses of XEN_DOM0
to a new XEN_PV_DOM0. (I'm not convinced all are really / should really
be PV-specific, but for starters I've tried to be conservative.)

For PVH Dom0 the hypervisor populates MADT with only x2APIC entries, so
without x2APIC support enabled in the kernel things aren't going to work
very well. (As opposed, DomU-s would only ever see LAPIC entries in MADT
as of now.) Note that this then requires PVH Dom0 to be 64-bit, as
X86_X2APIC depends on X86_64.

In the course of this xen_running_on_version_or_later() needs to be
available more broadly. Move it from a PV-specific to a generic file,
considering that what it does isn't really PV-specific at all anyway.

Note that xen/interface/version.h cannot be included on its own; in
enlighten.c, which uses SCHEDOP_* anyway, include xen/interface/sched.h
first to resolve the apparently sole missing type (xen_ulong_t).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>

--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -10,6 +10,8 @@
 
 #include <xen/xen.h>
 #include <xen/features.h>
+#include <xen/interface/sched.h>
+#include <xen/interface/version.h>
 #include <xen/page.h>
 
 #include <asm/xen/hypercall.h>
@@ -257,6 +259,21 @@ int xen_vcpu_setup(int cpu)
 	return ((per_cpu(xen_vcpu, cpu) == NULL) ? -ENODEV : 0);
 }
 
+/* Check if running on Xen version (major, minor) or later */
+bool xen_running_on_version_or_later(unsigned int major, unsigned int minor)
+{
+	unsigned int version;
+
+	if (!xen_domain())
+		return false;
+
+	version = HYPERVISOR_xen_version(XENVER_version, NULL);
+	if ((((version >> 16) == major) && ((version & 0xffff) >= minor)) ||
+		((version >> 16) > major))
+		return true;
+	return false;
+}
+
 void xen_reboot(int reason)
 {
 	struct sched_shutdown r = { .reason = reason };
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -142,22 +142,6 @@ static void __init xen_pv_guest_late_ini
 #endif
 }
 
-/* Check if running on Xen version (major, minor) or later */
-bool
-xen_running_on_version_or_later(unsigned int major, unsigned int minor)
-{
-	unsigned int version;
-
-	if (!xen_domain())
-		return false;
-
-	version = HYPERVISOR_xen_version(XENVER_version, NULL);
-	if ((((version >> 16) == major) && ((version & 0xffff) >= minor)) ||
-		((version >> 16) > major))
-		return true;
-	return false;
-}
-
 static __read_mostly unsigned int cpuid_leaf5_ecx_val;
 static __read_mostly unsigned int cpuid_leaf5_edx_val;
 
--- a/arch/x86/include/asm/xen/pci.h
+++ b/arch/x86/include/asm/xen/pci.h
@@ -14,16 +14,19 @@ static inline int pci_xen_hvm_init(void)
 	return -1;
 }
 #endif
-#if defined(CONFIG_XEN_DOM0)
+#ifdef CONFIG_XEN_PV_DOM0
 int __init pci_xen_initial_domain(void);
-int xen_find_device_domain_owner(struct pci_dev *dev);
-int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain);
-int xen_unregister_device_domain_owner(struct pci_dev *dev);
 #else
 static inline int __init pci_xen_initial_domain(void)
 {
 	return -1;
 }
+#endif
+#ifdef CONFIG_XEN_DOM0
+int xen_find_device_domain_owner(struct pci_dev *dev);
+int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain);
+int xen_unregister_device_domain_owner(struct pci_dev *dev);
+#else
 static inline int xen_find_device_domain_owner(struct pci_dev *dev)
 {
 	return -1;
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -113,7 +113,7 @@ static int acpi_register_gsi_xen_hvm(str
 				 false /* no mapping of GSI to PIRQ */);
 }
 
-#ifdef CONFIG_XEN_DOM0
+#ifdef CONFIG_XEN_PV_DOM0
 static int xen_register_gsi(u32 gsi, int triggering, int polarity)
 {
 	int rc, irq;
@@ -261,7 +261,7 @@ error:
 	return irq;
 }
 
-#ifdef CONFIG_XEN_DOM0
+#ifdef CONFIG_XEN_PV_DOM0
 static bool __read_mostly pci_seg_supported = true;
 
 static int xen_initdom_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
@@ -375,10 +375,10 @@ static void xen_initdom_restore_msi_irqs
 		WARN(ret && ret != -ENOSYS, "restore_msi -> %d\n", ret);
 	}
 }
-#else /* CONFIG_XEN_DOM0 */
+#else /* CONFIG_XEN_PV_DOM0 */
 #define xen_initdom_setup_msi_irqs	NULL
 #define xen_initdom_restore_msi_irqs	NULL
-#endif /* !CONFIG_XEN_DOM0 */
+#endif /* !CONFIG_XEN_PV_DOM0 */
 
 static void xen_teardown_msi_irqs(struct pci_dev *dev)
 {
@@ -555,7 +555,7 @@ int __init pci_xen_hvm_init(void)
 	return 0;
 }
 
-#ifdef CONFIG_XEN_DOM0
+#ifdef CONFIG_XEN_PV_DOM0
 int __init pci_xen_initial_domain(void)
 {
 	int irq;
@@ -583,6 +583,9 @@ int __init pci_xen_initial_domain(void)
 	}
 	return 0;
 }
+#endif
+
+#ifdef CONFIG_XEN_DOM0
 
 struct xen_device_domain_owner {
 	domid_t domain;
@@ -656,4 +659,4 @@ int xen_unregister_device_domain_owner(s
 	return 0;
 }
 EXPORT_SYMBOL_GPL(xen_unregister_device_domain_owner);
-#endif
+#endif /* CONFIG_XEN_DOM0 */
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -43,13 +43,9 @@ config XEN_PV_SMP
 	def_bool y
 	depends on XEN_PV && SMP
 
-config XEN_DOM0
-	bool "Xen PV Dom0 support"
-	default y
-	depends on XEN_PV && PCI_XEN && SWIOTLB_XEN
-	depends on X86_IO_APIC && ACPI && PCI
-	help
-	  Support running as a Xen PV Dom0 guest.
+config XEN_PV_DOM0
+	def_bool y
+	depends on XEN_PV && XEN_DOM0
 
 config XEN_PVHVM
 	def_bool y
@@ -86,3 +82,12 @@ config XEN_PVH
 	def_bool n
 	help
 	  Support for running as a Xen PVH guest.
+
+config XEN_DOM0
+	bool "Xen Dom0 support"
+	default XEN_PV
+	depends on (XEN_PV && SWIOTLB_XEN) || (XEN_PVH && X86_64)
+	depends on X86_IO_APIC && ACPI && PCI
+	select X86_X2APIC if XEN_PVH && X86_64
+	help
+	  Support running as a Xen Dom0 guest.
--- a/arch/x86/xen/Makefile
+++ b/arch/x86/xen/Makefile
@@ -45,7 +45,7 @@ obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= spinl
 
 obj-$(CONFIG_XEN_DEBUG_FS)	+= debugfs.o
 
-obj-$(CONFIG_XEN_DOM0)		+= vga.o
+obj-$(CONFIG_XEN_PV_DOM0)	+= vga.o
 
 obj-$(CONFIG_SWIOTLB_XEN)	+= pci-swiotlb-xen.o
 
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -109,7 +109,7 @@ static inline void xen_uninit_lock_cpu(i
 
 struct dom0_vga_console_info;
 
-#ifdef CONFIG_XEN_DOM0
+#ifdef CONFIG_XEN_PV_DOM0
 void __init xen_init_vga(const struct dom0_vga_console_info *, size_t size);
 #else
 static inline void __init xen_init_vga(const struct dom0_vga_console_info *info,
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -241,7 +241,7 @@ config XEN_PRIVCMD
 
 config XEN_ACPI_PROCESSOR
 	tristate "Xen ACPI processor"
-	depends on XEN && XEN_DOM0 && X86 && ACPI_PROCESSOR && CPU_FREQ
+	depends on XEN && XEN_PV_DOM0 && X86 && ACPI_PROCESSOR && CPU_FREQ
 	default m
 	help
 	  This ACPI processor uploads Power Management information to the Xen
@@ -259,7 +259,7 @@ config XEN_ACPI_PROCESSOR
 
 config XEN_MCE_LOG
 	bool "Xen platform mcelog"
-	depends on XEN_DOM0 && X86_MCE
+	depends on XEN_PV_DOM0 && X86_MCE
 	help
 	  Allow kernel fetching MCE error from Xen platform and
 	  converting it into Linux mcelog format for mcelog tools

[PATCH v2 3/9] xen/x86: make "earlyprintk=xen" work better for PVH Dom0

[Jan Beulich]

The xen_hvm_early_write() path better wouldn't be taken in this case;
while port 0xE9 can be used, the hypercall path is quite a bit more
efficient. Put that first, as it may also work for DomU-s (see also
xen_raw_console_write()).

While there also bail from the function when the first
domU_write_console() failed - later ones aren't going to succeed.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>

--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -632,17 +632,16 @@ static void xenboot_write_console(struct
 	unsigned int linelen, off = 0;
 	const char *pos;
 
+	if (dom0_write_console(0, string, len) >= 0)
+		return;
+
 	if (!xen_pv_domain()) {
 		xen_hvm_early_write(0, string, len);
 		return;
 	}
 
-	dom0_write_console(0, string, len);
-
-	if (xen_initial_domain())
+	if (domU_write_console(0, "(early) ", 8) < 0)
 		return;
-
-	domU_write_console(0, "(early) ", 8);
 	while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
 		linelen = pos-string+off;
 		if (off + linelen > len)

[PATCH v2 4/9] xen/x86: allow "earlyprintk=xen" to work for PV Dom0

[Jan Beulich]

With preferred consoles "tty" and "hvc" announced as preferred,
registering "xenboot" early won't result in use of the console: It also
needs to be registered as preferred. Generalize this from being DomU-
only so far.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
---
v2: Re-base.

--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -1348,7 +1348,6 @@ asmlinkage __visible void __init xen_sta
 	boot_params.hdr.hardware_subarch = X86_SUBARCH_XEN;
 
 	if (!xen_initial_domain()) {
-		add_preferred_console("xenboot", 0, NULL);
 		if (pci_xen)
 			x86_init.pci.arch_init = pci_xen_init;
 		x86_platform.set_legacy_features =
@@ -1393,6 +1392,7 @@ asmlinkage __visible void __init xen_sta
 #endif
 	}
 
+	add_preferred_console("xenboot", 0, NULL);
 	if (!boot_params.screen_info.orig_video_isVGA)
 		add_preferred_console("tty", 0, NULL);
 	add_preferred_console("hvc", 0, NULL);

[PATCH v2 5/9] xen/x86: make "earlyprintk=xen" work for HVM/PVH DomU

[Jan Beulich]

xenboot_write_console() is dealing with these quite fine so I don't see
why xenboot_console_setup() would return -ENOENT in this case.

Adjust documentation accordingly.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>

--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1266,7 +1266,7 @@
 			The VGA and EFI output is eventually overwritten by
 			the real console.
 
-			The xen output can only be used by Xen PV guests.
+			The xen option can only be used in Xen domains.
 
 			The sclp output can only be used on s390.
 
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -618,10 +618,8 @@ static int __init xenboot_console_setup(
 {
 	static struct xencons_info xenboot;
 
-	if (xen_initial_domain())
+	if (xen_initial_domain() || !xen_pv_domain())
 		return 0;
-	if (!xen_pv_domain())
-		return -ENODEV;
 
 	return xencons_info_pv_init(&xenboot, 0);
 }

[PATCH v2 6/9] xen/x86: generalize preferred console model from PV to PVH Dom0

[Jan Beulich]

Without announcing hvc0 as preferred it won't get used as long as tty0
gets registered earlier. This is particularly problematic with there not
being any screen output for PVH Dom0 when the screen is in graphics
mode, as the necessary information doesn't get conveyed yet from the
hypervisor.

Follow PV's model, but be conservative and do this for Dom0 only for
now.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
---
Prior to 418492ba40b2 ("x86/virt/xen: Use guest_late_init to detect Xen
PVH guest") x86_init.oem.arch_setup was already used by PVH, so I assume
the use of this hook is acceptable here.

Seeing that change, I wonder in how far setting xen_pvh to true only in
xen_hvm_guest_late_init() can really work: This hook, as its name says,
gets called pretty late; any decision taken earlier might have been
wrong. One such wrong decision is what gets added here - preferred
consoles won't be registered when taking that path. While adding a 2nd
call there might work, aiui they would better be registered prior to
parse_early_param(), i.e. before "earlyprintk=" gets evaluated.

I also consider tying "detecting" PVH mode to the no-VGA and no-CMOS-RTC
FADT flags as problematic looking forward: There may conceivably be
"legacy free" HVM guests down the road, yet they shouldn't be mistaken
for being PVH. Most of the XEN_X86_EMU_* controlled functionality would
seem unsuitable for the same reason; presence/absence of
XENFEAT_hvm_pirqs (tied to XEN_X86_EMU_USE_PIRQ) might be sufficiently
reliable an indicator. Question there is whether the separation
introduced by Xen commit b96b50004804 ("x86: remove XENFEAT_hvm_pirqs
for PVHv2 guests") came early enough in the process of enabling PVHv2.
Plus I'm not sure a HVM guest without pass-through enabled couldn't be
run with this off (i.e. by relaxing emulation_flags_ok() and having the
tool stack not request this emulation in such cases).

I think the approach here might be equally applicable for DomU, albeit
potentially pointless (i.e. dropping the conditional might make sense
even if simply benign there): A PVH DomU ought to never come with a VGA
console. Yet even then a dummy one may still get registered and would
take precedence over hvc?

--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -3,6 +3,7 @@
 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
 #include <linux/memblock.h>
 #endif
+#include <linux/console.h>
 #include <linux/cpu.h>
 #include <linux/kexec.h>
 #include <linux/slab.h>
@@ -18,6 +19,7 @@
 #include <asm/xen/hypervisor.h>
 #include <asm/cpu.h>
 #include <asm/e820/api.h> 
+#include <asm/setup.h>
 
 #include "xen-ops.h"
 #include "smp.h"
@@ -274,6 +276,16 @@ bool xen_running_on_version_or_later(uns
 	return false;
 }
 
+void __init xen_add_preferred_consoles(void)
+{
+	add_preferred_console("xenboot", 0, NULL);
+	if (!boot_params.screen_info.orig_video_isVGA)
+		add_preferred_console("tty", 0, NULL);
+	add_preferred_console("hvc", 0, NULL);
+	if (boot_params.screen_info.orig_video_isVGA)
+		add_preferred_console("tty", 0, NULL);
+}
+
 void xen_reboot(int reason)
 {
 	struct sched_shutdown r = { .reason = reason };
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -28,7 +28,6 @@
 #include <linux/mm.h>
 #include <linux/page-flags.h>
 #include <linux/highmem.h>
-#include <linux/console.h>
 #include <linux/pci.h>
 #include <linux/gfp.h>
 #include <linux/edd.h>
@@ -1392,12 +1391,7 @@ asmlinkage __visible void __init xen_sta
 #endif
 	}
 
-	add_preferred_console("xenboot", 0, NULL);
-	if (!boot_params.screen_info.orig_video_isVGA)
-		add_preferred_console("tty", 0, NULL);
-	add_preferred_console("hvc", 0, NULL);
-	if (boot_params.screen_info.orig_video_isVGA)
-		add_preferred_console("tty", 0, NULL);
+	xen_add_preferred_consoles();
 
 #ifdef CONFIG_PCI
 	/* PCI BIOS service won't work from a PV guest. */
--- a/arch/x86/xen/enlighten_pvh.c
+++ b/arch/x86/xen/enlighten_pvh.c
@@ -36,6 +36,9 @@ void __init xen_pvh_init(struct boot_par
 	pfn = __pa(hypercall_page);
 	wrmsr_safe(msr, (u32)pfn, (u32)(pfn >> 32));
 
+	if (xen_initial_domain())
+		x86_init.oem.arch_setup = xen_add_preferred_consoles;
+
 	xen_efi_init(boot_params);
 }
 
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -118,6 +118,8 @@ static inline void __init xen_init_vga(c
 }
 #endif
 
+void xen_add_preferred_consoles(void);
+
 void __init xen_init_apic(void);
 
 #ifdef CONFIG_XEN_EFI

[PATCH v2 7/9] xen/x86: hook up xen_banner() also for PVH

[Jan Beulich]

This was effectively lost while dropping PVHv1 code. Move the function
and arrange for it to be called the same way as done in PV mode. Clearly
this then needs re-introducing the XENFEAT_mmu_pt_update_preserve_ad
check that was recently removed, as that's a PV-only feature.

Since the string pointed at by pv_info.name describes the mode, drop
"paravirtualized" from the log message while moving the code.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v2: Add blank line. Drop "paravirtualized" from log message. Wrap a long
    line.

--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -261,6 +261,20 @@ int xen_vcpu_setup(int cpu)
 	return ((per_cpu(xen_vcpu, cpu) == NULL) ? -ENODEV : 0);
 }
 
+void __init xen_banner(void)
+{
+	unsigned version = HYPERVISOR_xen_version(XENVER_version, NULL);
+	struct xen_extraversion extra;
+
+	HYPERVISOR_xen_version(XENVER_extraversion, &extra);
+
+	pr_info("Booting kernel on %s\n", pv_info.name);
+	pr_info("Xen version: %u.%u%s%s\n",
+		version >> 16, version & 0xffff, extra.extraversion,
+		xen_feature(XENFEAT_mmu_pt_update_preserve_ad)
+		? " (preserve-AD)" : "");
+}
+
 /* Check if running on Xen version (major, minor) or later */
 bool xen_running_on_version_or_later(unsigned int major, unsigned int minor)
 {
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -108,17 +108,6 @@ struct tls_descs {
  */
 static DEFINE_PER_CPU(struct tls_descs, shadow_tls_desc);
 
-static void __init xen_banner(void)
-{
-	unsigned version = HYPERVISOR_xen_version(XENVER_version, NULL);
-	struct xen_extraversion extra;
-	HYPERVISOR_xen_version(XENVER_extraversion, &extra);
-
-	pr_info("Booting paravirtualized kernel on %s\n", pv_info.name);
-	pr_info("Xen version: %d.%d%s (preserve-AD)\n",
-		version >> 16, version & 0xffff, extra.extraversion);
-}
-
 static void __init xen_pv_init_platform(void)
 {
 	populate_extra_pte(fix_to_virt(FIX_PARAVIRT_BOOTMAP));
--- a/arch/x86/xen/enlighten_pvh.c
+++ b/arch/x86/xen/enlighten_pvh.c
@@ -38,6 +38,7 @@ void __init xen_pvh_init(struct boot_par
 
 	if (xen_initial_domain())
 		x86_init.oem.arch_setup = xen_add_preferred_consoles;
+	x86_init.oem.banner = xen_banner;
 
 	xen_efi_init(boot_params);
 }
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -51,6 +51,7 @@ void __init xen_remap_memory(void);
 phys_addr_t __init xen_find_free_area(phys_addr_t size);
 char * __init xen_memory_setup(void);
 void __init xen_arch_setup(void);
+void xen_banner(void);
 void xen_enable_sysenter(void);
 void xen_enable_syscall(void);
 void xen_vcpu_restore(void);

[PATCH v2 8/9] x86/PVH: adjust function/data placement

[Jan Beulich]

Two of the variables can live in .init.data, allowing the open-coded
placing in .data to go away. Another "variable" is used to communicate a
size value only to very early assembly code, which hence can be both
const and live in .init.*. Additionally two functions were lacking
__init annotations.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>

--- a/arch/x86/platform/pvh/enlighten.c
+++ b/arch/x86/platform/pvh/enlighten.c
@@ -16,15 +16,15 @@
 /*
  * PVH variables.
  *
- * pvh_bootparams and pvh_start_info need to live in the data segment since
+ * pvh_bootparams and pvh_start_info need to live in a data segment since
  * they are used after startup_{32|64}, which clear .bss, are invoked.
  */
-struct boot_params pvh_bootparams __section(".data");
-struct hvm_start_info pvh_start_info __section(".data");
+struct boot_params __initdata pvh_bootparams;
+struct hvm_start_info __initdata pvh_start_info;
 
-unsigned int pvh_start_info_sz = sizeof(pvh_start_info);
+const unsigned int __initconst pvh_start_info_sz = sizeof(pvh_start_info);
 
-static u64 pvh_get_root_pointer(void)
+static u64 __init pvh_get_root_pointer(void)
 {
 	return pvh_start_info.rsdp_paddr;
 }
@@ -107,7 +107,7 @@ void __init __weak xen_pvh_init(struct b
 	BUG();
 }
 
-static void hypervisor_specific_init(bool xen_guest)
+static void __init hypervisor_specific_init(bool xen_guest)
 {
 	if (xen_guest)
 		xen_pvh_init(&pvh_bootparams);

[PATCH v2 9/9] xen/x86: adjust data placement

[Jan Beulich]

Both xen_pvh and xen_start_flags get written just once early during
init. Using the respective annotation then allows the open-coded placing
in .data to go away.

Additionally the former, like the latter, wants exporting, or else
xen_pvh_domain() can't be used from modules.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
I have to admit that it is completely unclear to me which form of
exporting I should have used: xen_domain_type is GPL-only while
xen_start_flags is not, yet both are used in similar ways, extending to
xen_pvh. Picking the GPL version was suggested by Jürgen.
---
v2: Use EXPORT_SYMBOL_GPL().

--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -75,7 +75,7 @@ EXPORT_SYMBOL_GPL(xen_have_vector_callba
  */
 enum xen_domain_type __ro_after_init xen_domain_type = XEN_NATIVE;
 EXPORT_SYMBOL_GPL(xen_domain_type);
-uint32_t xen_start_flags __section(".data") = 0;
+uint32_t __ro_after_init xen_start_flags;
 EXPORT_SYMBOL(xen_start_flags);
 
 /*
--- a/arch/x86/xen/enlighten_pvh.c
+++ b/arch/x86/xen/enlighten_pvh.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/acpi.h>
+#include <linux/export.h>
 
 #include <xen/hvc-console.h>
 
@@ -18,10 +19,11 @@
 /*
  * PVH variables.
  *
- * The variable xen_pvh needs to live in the data segment since it is used
+ * The variable xen_pvh needs to live in a data segment since it is used
  * after startup_{32|64} is invoked, which will clear the .bss segment.
  */
-bool xen_pvh __section(".data") = 0;
+bool __ro_after_init xen_pvh;
+EXPORT_SYMBOL_GPL(xen_pvh);
 
 void __init xen_pvh_init(struct boot_params *boot_params)
 {

Re: [PATCH v2 7/9] xen/x86: hook up xen_banner() also for PVH

[Juergen Gross]

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On 30.09.21 14:19, Jan Beulich wrote:
> This was effectively lost while dropping PVHv1 code. Move the function
> and arrange for it to be called the same way as done in PV mode. Clearly
> this then needs re-introducing the XENFEAT_mmu_pt_update_preserve_ad
> check that was recently removed, as that's a PV-only feature.
> 
> Since the string pointed at by pv_info.name describes the mode, drop
> "paravirtualized" from the log message while moving the code.
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

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


Juergen

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Re: [PATCH v2 9/9] xen/x86: adjust data placement

[Juergen Gross]

[-- Attachment #1.1.1: Type: text/plain, Size: 447 bytes --]

On 30.09.21 14:21, Jan Beulich wrote:
> Both xen_pvh and xen_start_flags get written just once early during
> init. Using the respective annotation then allows the open-coded placing
> in .data to go away.
> 
> Additionally the former, like the latter, wants exporting, or else
> xen_pvh_domain() can't be used from modules.
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

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


Juergen

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Re: [PATCH v2 0/9] xen/x86: PVH Dom0 fixes and fallout adjustments

[Juergen Gross]

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On 30.09.21 14:12, Jan Beulich wrote:
> In order to try to debug hypervisor side breakage from XSA-378 I found
> myself urged to finally give PVH Dom0 a try. Sadly things didn't work
> quite as expected. In the course of investigating these issues I actually
> spotted one piece of PV Dom0 breakage as well, a fix for which is also
> included here.
> 
> There are one immediate remaining issues: Dom0, unlike in the PV case,
> cannot access the screen (to use as a console) when in a non-default
> mode (i.e. not 80x25 text), as the necessary information (in particular
> about VESA-bases LFB modes) is not communicated. On the hypervisor side
> this looks like deliberate behavior, but it is unclear to me what the
> intentions were towards an alternative model. (X may be able to access
> the screen depending on whether it has a suitable driver besides the
> presently unusable /dev/fb<N> based one.)
> 
> v2 merely addresses small review comments in patches 7 and 9 (see there).
> 
> 1: xen/x86: prevent PVH type from getting clobbered
> 2: xen/x86: allow PVH Dom0 without XEN_PV=y
> 3: xen/x86: make "earlyprintk=xen" work better for PVH Dom0
> 4: xen/x86: allow "earlyprintk=xen" to work for PV Dom0
> 5: xen/x86: make "earlyprintk=xen" work for HVM/PVH DomU
> 6: xen/x86: generalize preferred console model from PV to PVH Dom0
> 7: xen/x86: hook up xen_banner() also for PVH
> 8: x86/PVH: adjust function/data placement
> 9: xen/x86: adjust data placement

Series pushed to xen/tip.git for-linus-5.15b


Juergen


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