linux-stable.git/arch/x86/include, branch v4.4

x86/paravirt: Prevent rtc_cmos platform device init on PV guests

2015-12-19T20:35:13+00:00

Adding the rtc platform device in non-privileged Xen PV guests causes
an IRQ conflict because these guests do not have legacy PIC and may
allocate irqs in the legacy range.

In a single VCPU Xen PV guest we should have:

/proc/interrupts:
           CPU0
  0:       4934  xen-percpu-virq      timer0
  1:          0  xen-percpu-ipi       spinlock0
  2:          0  xen-percpu-ipi       resched0
  3:          0  xen-percpu-ipi       callfunc0
  4:          0  xen-percpu-virq      debug0
  5:          0  xen-percpu-ipi       callfuncsingle0
  6:          0  xen-percpu-ipi       irqwork0
  7:        321   xen-dyn-event     xenbus
  8:         90   xen-dyn-event     hvc_console
  ...

But hvc_console cannot get its interrupt because it is already in use
by rtc0 and the console does not work.

  genirq: Flags mismatch irq 8. 00000000 (hvc_console) vs. 00000000 (rtc0)

We can avoid this problem by realizing that unprivileged PV guests (both
Xen and lguests) are not supposed to have rtc_cmos device and so
adding it is not necessary.

Privileged guests (i.e. Xen's dom0) do use it but they should not have
irq conflicts since they allocate irqs above legacy range (above
gsi_top, in fact).

Instead of explicitly testing whether the guest is privileged we can
extend pv_info structure to include information about guest's RTC
support.

Reported-and-tested-by: Sander Eikelenboom 
Signed-off-by: David Vrabel 
Signed-off-by: Boris Ostrovsky 
Cc: vkuznets@redhat.com
Cc: xen-devel@lists.xenproject.org
Cc: konrad.wilk@oracle.com
Cc: stable@vger.kernel.org # 4.2+
Link: http://lkml.kernel.org/r/1449842873-2613-1-git-send-email-boris.ostrovsky@oracle.com
Signed-off-by: Thomas Gleixner

x86/xen: Avoid fast syscall path for Xen PV guests

2015-12-19T08:55:52+00:00

After 32-bit syscall rewrite, and specifically after commit:

  5f310f739b4c ("x86/entry/32: Re-implement SYSENTER using the new C path")

... the stack frame that is passed to xen_sysexit is no longer a
"standard" one (i.e. it's not pt_regs).

Since we end up calling xen_iret from xen_sysexit we don't need
to fix up the stack and instead follow entry_SYSENTER_32's IRET
path directly to xen_iret.

We can do the same thing for compat mode even though stack does
not need to be fixed. This will allow us to drop usergs_sysret32
paravirt op (in the subsequent patch)

Suggested-by: Andy Lutomirski 
Signed-off-by: Boris Ostrovsky 
Reviewed-by: Borislav Petkov 
Acked-by: Andy Lutomirski 
Cc: Andrew Morton 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: david.vrabel@citrix.com
Cc: konrad.wilk@oracle.com
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1447970147-1733-2-git-send-email-boris.ostrovsky@oracle.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Thomas Gleixner

x86/mm: Fix regression with huge pages on PAE

2015-12-04T08:14:27+00:00

Recent PAT patchset has caused issue on 32-bit PAE machines:

  page:eea45000 count:0 mapcount:-128 mapping:  (null) index:0x0 flags: 0x40000000()
  page dumped because: VM_BUG_ON_PAGE(page_mapcount(page) < 0)
  ------------[ cut here ]------------
  kernel BUG at /home/build/linux-boris/mm/huge_memory.c:1485!
  invalid opcode: 0000 [#1] SMP
  [...]
  Call Trace:
   unmap_single_vma
   ? __wake_up
   unmap_vmas
   unmap_region
   do_munmap
   vm_munmap
   SyS_munmap
   do_fast_syscall_32
   ? __do_page_fault
   sysenter_past_esp
  Code: ...
  EIP: [] zap_huge_pmd+0x240/0x260 SS:ESP 0068:f6459d98

The problem is in pmd_pfn_mask() and pmd_flags_mask(). These
helpers use PMD_PAGE_MASK to calculate resulting mask.
PMD_PAGE_MASK is 'unsigned long', not 'unsigned long long' as
phys_addr_t is on 32-bit PAE (ARCH_PHYS_ADDR_T_64BIT). As a
result, the upper bits of resulting mask get truncated.

pud_pfn_mask() and pud_flags_mask() aren't problematic since we
don't have PUD page table level on 32-bit systems, but it's
reasonable to keep them consistent with PMD counterpart.

Introduce PHYSICAL_PMD_PAGE_MASK and PHYSICAL_PUD_PAGE_MASK in
addition to existing PHYSICAL_PAGE_MASK and reworks helpers to
use them.

Reported-and-Tested-by: Boris Ostrovsky 
Signed-off-by: Kirill A. Shutemov 
[ Fix -Woverflow warnings from the realmode code. ]
Signed-off-by: Borislav Petkov 
Reviewed-by: Toshi Kani 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Jürgen Gross 
Cc: Linus Torvalds 
Cc: Mel Gorman 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: elliott@hpe.com
Cc: konrad.wilk@oracle.com
Cc: linux-mm 
Fixes: f70abb0fc3da ("x86/asm: Fix pud/pmd interfaces to handle large PAT bit")
Link: http://lkml.kernel.org/r/1448878233-11390-2-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar 

Signed-off-by: Ingo Molnar

Merge branch 'pm-tools'

2015-11-16T21:57:02+00:00

* pm-tools:
  x86: remove unused definition of MSR_NHM_PLATFORM_INFO
  tools/power turbostat: use new name for MSR_PLATFORM_INFO

Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-11-15T17:32:59+00:00

Pull x86 fixes from Thomas Gleixner:
 "A couple of fixes and updates related to x86:

   - Fix the W+X check regression on XEN

   - The real fix for the low identity map trainwreck

   - Probe legacy PIC early instead of unconditionally allocating legacy
     irqs

   - Add cpu verification to long mode entry

   - Adjust the cache topology to AMD Fam17H systems

   - Let Merrifield use the TSC across S3"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cpu: Call verify_cpu() after having entered long mode too
  x86/setup: Fix low identity map for >= 2GB kernel range
  x86/mm: Skip the hypervisor range when walking PGD
  x86/AMD: Fix last level cache topology for AMD Fam17h systems
  x86/irq: Probe for PIC presence before allocating descs for legacy IRQs
  x86/cpu/intel: Enable X86_FEATURE_NONSTOP_TSC_S3 for Merrifield

x86: remove unused definition of MSR_NHM_PLATFORM_INFO

2015-11-13T22:28:01+00:00

MSR_NHM_PLATFORM_INFO has been replaced by...
MSR_PLATFORM_INFO

Signed-off-by: Len Brown 
Signed-off-by: Rafael J. Wysocki

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2015-11-12T22:34:06+00:00

Pull second batch of kvm updates from Paolo Bonzini:
 "Four changes:

   - x86: work around two nasty cases where a benign exception occurs
     while another is being delivered.  The endless stream of exceptions
     causes an infinite loop in the processor, which not even NMIs or
     SMIs can interrupt; in the virt case, there is no possibility to
     exit to the host either.

   - x86: support for Skylake per-guest TSC rate.  Long supported by
     AMD, the patches mostly move things from there to common
     arch/x86/kvm/ code.

   - generic: remove local_irq_save/restore from the guest entry and
     exit paths when context tracking is enabled.  The patches are a few
     months old, but we discussed them again at kernel summit.  Andy
     will pick up from here and, in 4.5, try to remove it from the user
     entry/exit paths.

   - PPC: Two bug fixes, see merge commit 370289756becc for details"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (21 commits)
  KVM: x86: rename update_db_bp_intercept to update_bp_intercept
  KVM: svm: unconditionally intercept #DB
  KVM: x86: work around infinite loop in microcode when #AC is delivered
  context_tracking: avoid irq_save/irq_restore on guest entry and exit
  context_tracking: remove duplicate enabled check
  KVM: VMX: Dump TSC multiplier in dump_vmcs()
  KVM: VMX: Use a scaled host TSC for guest readings of MSR_IA32_TSC
  KVM: VMX: Setup TSC scaling ratio when a vcpu is loaded
  KVM: VMX: Enable and initialize VMX TSC scaling
  KVM: x86: Use the correct vcpu's TSC rate to compute time scale
  KVM: x86: Move TSC scaling logic out of call-back read_l1_tsc()
  KVM: x86: Move TSC scaling logic out of call-back adjust_tsc_offset()
  KVM: x86: Replace call-back compute_tsc_offset() with a common function
  KVM: x86: Replace call-back set_tsc_khz() with a common function
  KVM: x86: Add a common TSC scaling function
  KVM: x86: Add a common TSC scaling ratio field in kvm_vcpu_arch
  KVM: x86: Collect information for setting TSC scaling ratio
  KVM: x86: declare a few variables as __read_mostly
  KVM: x86: merge handle_mmio_page_fault and handle_mmio_page_fault_common
  KVM: PPC: Book3S HV: Don't dynamically split core when already split
  ...

KVM: x86: rename update_db_bp_intercept to update_bp_intercept

2015-11-10T11:06:25+00:00

Because #DB is now intercepted unconditionally, this callback
only operates on #BP for both VMX and SVM.

Signed-off-by: Paolo Bonzini

KVM: x86: work around infinite loop in microcode when #AC is delivered

2015-11-10T11:06:24+00:00

It was found that a guest can DoS a host by triggering an infinite
stream of "alignment check" (#AC) exceptions.  This causes the
microcode to enter an infinite loop where the core never receives
another interrupt.  The host kernel panics pretty quickly due to the
effects (CVE-2015-5307).

Signed-off-by: Eric Northup 
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini

KVM: VMX: Enable and initialize VMX TSC scaling

2015-11-10T11:06:19+00:00

This patch exhances kvm-intel module to enable VMX TSC scaling and
collects information of TSC scaling ratio during initialization.

Signed-off-by: Haozhong Zhang 
Signed-off-by: Paolo Bonzini