Disable RTC in non-privileged Xen PV guests - unused there and breaks DispVMs
Thanks @esheltone for the patch.
This commit is contained in:
Marek Marczykowski-Górecki
parent
d262e5e5ad
commit
3d4f4bcf16
153
patches.xen/fix-rtc-cmos.patch
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153
patches.xen/fix-rtc-cmos.patch
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@ -0,0 +1,153 @@
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Adding the rtc platform device in non-privileged Xen PV guests causes
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an IRQ conflict because these guests do not have legacy PIC and may
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allocate irqs in the legacy range.
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In a single VCPU Xen PV guest we should have:
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/proc/interrupts:
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CPU0
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0: 4934 xen-percpu-virq timer0
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1: 0 xen-percpu-ipi spinlock0
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2: 0 xen-percpu-ipi resched0
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3: 0 xen-percpu-ipi callfunc0
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4: 0 xen-percpu-virq debug0
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5: 0 xen-percpu-ipi callfuncsingle0
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6: 0 xen-percpu-ipi irqwork0
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7: 321 xen-dyn-event xenbus
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8: 90 xen-dyn-event hvc_console
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...
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But hvc_console cannot get its interrupt because it is already in use
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by rtc0 and the console does not work.
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genirq: Flags mismatch irq 8. 00000000 (hvc_console) vs. 00000000 (rtc0)
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We can avoid this problem by realizing that unprivileged PV guests (both
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Xen and lguests) are not supposed to have rtc_cmos device and so
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adding it is not necessary.
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Privileged guests (i.e. Xen's dom0) do use it but they should not have
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irq conflicts since they allocate irqs above legacy range (above
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gsi_top, in fact).
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Instead of explicitly testing whether the guest is privileged we can
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extend pv_info structure to include information about guest's RTC
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support.
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Reported-by: Sander Eikelenboom <linux@xxxxxxxxxxxxxx>
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Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
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Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
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Tested-by: Sander Eikelenboom <linux@xxxxxxxxxxxxxx>
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Cc: stable@xxxxxxxxxxxxxxx # 4.2+
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---
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v2: Xen dom0 still should have access to cmos_rts. Extend pv_info structure to
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allow specifying which PV-enabled guests are allowed to access RTC
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arch/x86/include/asm/paravirt.h | 6 ++++++
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arch/x86/include/asm/paravirt_types.h | 5 +++++
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arch/x86/include/asm/processor.h | 1 +
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arch/x86/kernel/rtc.c | 3 +++
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arch/x86/lguest/boot.c | 1 +
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arch/x86/xen/enlighten.c | 4 +++-
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6 files changed, 19 insertions(+), 1 deletion(-)
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diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
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index 10d0596..c759b3c 100644
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--- a/arch/x86/include/asm/paravirt.h
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+++ b/arch/x86/include/asm/paravirt.h
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@@ -19,6 +19,12 @@ static inline int paravirt_enabled(void)
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return pv_info.paravirt_enabled;
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}
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+static inline int paravirt_has_feature(unsigned int feature)
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+{
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+ WARN_ON_ONCE(!pv_info.paravirt_enabled);
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+ return (pv_info.features & feature);
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+}
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+
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static inline void load_sp0(struct tss_struct *tss,
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struct thread_struct *thread)
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{
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diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
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index 31247b5..3d44191 100644
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--- a/arch/x86/include/asm/paravirt_types.h
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+++ b/arch/x86/include/asm/paravirt_types.h
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@@ -70,9 +70,14 @@ struct pv_info {
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#endif
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int paravirt_enabled;
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+ unsigned int features; /* valid only if paravirt_enabled is set */
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const char *name;
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};
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+#define paravirt_has(x) paravirt_has_feature(PV_SUPPORTED_##x)
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+/* Supported features */
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+#define PV_SUPPORTED_RTC (1<<0)
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+
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struct pv_init_ops {
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/*
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* Patch may replace one of the defined code sequences with
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diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
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index 6752225..2d5a50c 100644
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--- a/arch/x86/include/asm/processor.h
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+++ b/arch/x86/include/asm/processor.h
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@@ -472,6 +472,7 @@ static inline unsigned long current_top_of_stack(void)
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#else
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#define __cpuid native_cpuid
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#define paravirt_enabled() 0
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+#define paravirt_has(x) 0
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static inline void load_sp0(struct tss_struct *tss,
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struct thread_struct *thread)
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diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
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index cd96852..4af8d06 100644
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--- a/arch/x86/kernel/rtc.c
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+++ b/arch/x86/kernel/rtc.c
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@@ -200,6 +200,9 @@ static __init int add_rtc_cmos(void)
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}
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#endif
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+ if (paravirt_enabled() && !paravirt_has(RTC))
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+ return -ENODEV;
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+
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platform_device_register(&rtc_device);
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dev_info(&rtc_device.dev,
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"registered platform RTC device (no PNP device found)\n");
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diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
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index a0d09f6..a43b2ea 100644
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--- a/arch/x86/lguest/boot.c
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+++ b/arch/x86/lguest/boot.c
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@@ -1414,6 +1414,7 @@ __init void lguest_init(void)
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pv_info.kernel_rpl = 1;
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/* Everyone except Xen runs with this set. */
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pv_info.shared_kernel_pmd = 1;
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+ pv_info.features = 0;
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/*
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* We set up all the lguest overrides for sensitive operations. These
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diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
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index d315151..b7de78b 100644
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--- a/arch/x86/xen/enlighten.c
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+++ b/arch/x86/xen/enlighten.c
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@@ -1192,7 +1192,7 @@ static const struct pv_info xen_info __initconst = {
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#ifdef CONFIG_X86_64
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.extra_user_64bit_cs = FLAT_USER_CS64,
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#endif
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-
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+ .features = 0,
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.name = "Xen",
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};
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@@ -1535,6 +1535,8 @@ asmlinkage __visible void __init xen_start_kernel(void)
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/* Install Xen paravirt ops */
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pv_info = xen_info;
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+ if (xen_initial_domain())
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+ pv_info.features |= PV_SUPPORTED_RTC;
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pv_init_ops = xen_init_ops;
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pv_apic_ops = xen_apic_ops;
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if (!xen_pvh_domain()) {
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--
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1.8.1.4
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@ -3,6 +3,7 @@ patches.rpmify/makefile-after_link.patch
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patches.xen/0001-Revert-xen-xenbus-Avoid-synchronous-wait-on-XenBus-s.patch
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patches.xen/0001-xen-fix-deadlock-on-proc-xen-xenbus-access.patch
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patches.xen/xen-netfront-detach-crash.patch
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patches.xen/fix-rtc-cmos.patch
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# Additional features
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#patches.xen/pvops-0100-usb-xen-pvusb-driver.patch
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