Zhang Xiantao [Sat, 20 Oct 2007 07:34:38 +0000 (15:34 +0800)]
KVM: Portability: Split kvm_vcpu into arch dependent and independent parts (part 1)
First step to split kvm_vcpu. Currently, we just use an macro to define
the common fields in kvm_vcpu for all archs, and all archs need to define
its own kvm_vcpu struct.
Signed-off-by: Zhang Xiantao <xiantao.zhang@intel.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
Anthony Liguori [Thu, 18 Oct 2007 14:59:34 +0000 (09:59 -0500)]
KVM: Allocate userspace memory for older userspace
Allocate a userspace buffer for older userspaces. Also eliminate phys_mem
buffer. The memset() in kvmctl really kills initial memory usage but swapping
works even with old userspaces.
A side effect is that maximum guest side is reduced for older userspace on
i386.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
KVM: Use virtual cpu accounting if available for guest times.
ppc and s390 offer the possibility to track process times precisely
by looking at cpu timer on every context switch, irq, softirq etc.
We can use that infrastructure as well for guest time accounting.
We need to account the used time before we change the state.
This patch adds a call to account_system_vtime to kvm_guest_enter
and kvm_guest exit. If CONFIG_VIRT_CPU_ACCOUNTING is not set,
account_system_vtime is defined in hardirq.h as an empty function,
which means this patch does not change the behaviour on other
platforms.
I compile tested this patch on x86 and function tested the patch on
s390.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
Izik Eidus [Thu, 18 Oct 2007 09:09:33 +0000 (11:09 +0200)]
KVM: MMU: Partial swapping of guest memory
This allows guest memory to be swapped. Pages which are currently mapped
via shadow page tables are pinned into memory, but all other pages can
be freely swapped.
The patch makes gfn_to_page() elevate the page's reference count, and
introduces kvm_release_page() that pairs with it.
Signed-off-by: Izik Eidus <izike@qumranet.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
Izik Eidus [Tue, 16 Oct 2007 12:43:46 +0000 (14:43 +0200)]
KVM: MMU: Keep a reverse mapping of non-writable translations
The current kvm mmu only reverse maps writable translation. This is used
to write-protect a page in case it becomes a pagetable.
But with swapping support, we need a reverse mapping of read-only pages as
well: when we evict a page, we need to remove any mapping to it, whether
writable or not.
Signed-off-by: Izik Eidus <izike@qumranet.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
Avi Kivity [Wed, 17 Oct 2007 10:18:47 +0000 (12:18 +0200)]
KVM: MMU: Simplify page table walker
Simplify the walker level loop not to carry so much information from one
loop to the next. In addition to being complex, this made kmap_atomic()
critical sections difficult to manage.
As a result of this change, kmap_atomic() sections are limited to actually
touching the guest pte, which allows the other functions called from the
walker to do sleepy operations. This will happen when we enable swapping.
Avi Kivity [Tue, 16 Oct 2007 14:23:22 +0000 (16:23 +0200)]
KVM: Move apic timer interrupt backlog processing to common code
Beside the obvious goodness of making code more common, this prevents
a livelock with the next patch which moves interrupt injection out of the
critical section.
Qing He [Mon, 24 Sep 2007 09:39:41 +0000 (17:39 +0800)]
KVM: apic round robin cleanup
If no apic is enabled in the bitmap of an interrupt delivery with delivery
mode of lowest priority, a warning should be reported rather than select
a fallback vcpu
Signed-off-by: Qing He <qing.he@intel.com> Signed-off-by: Eddie (Yaozu) Dong <eddie.dong@intel.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
Carsten Otte [Thu, 11 Oct 2007 17:16:52 +0000 (19:16 +0200)]
KVM: Portability: split kvm_vcpu_ioctl
This patch splits kvm_vcpu_ioctl into archtecture independent parts, and
x86 specific parts which go to kvm_arch_vcpu_ioctl in x86.c.
Common ioctls for all architectures are:
KVM_RUN, KVM_GET/SET_(S-)REGS, KVM_TRANSLATE, KVM_INTERRUPT,
KVM_DEBUG_GUEST, KVM_SET_SIGNAL_MASK, KVM_GET/SET_FPU
Note that some PPC chips don't have an FPU, so we might need an #ifdef
around KVM_GET/SET_FPU one day.
x86 specific ioctls are:
KVM_GET/SET_LAPIC, KVM_SET_CPUID, KVM_GET/SET_MSRS
An interresting aspect is vcpu_load/vcpu_put. We now have a common
vcpu_load/put which does the preemption stuff, and an architecture
specific kvm_arch_vcpu_load/put. In the x86 case, this one calls the
vmx/svm function defined in kvm_x86_ops.
Signed-off-by: Carsten Otte <cotte@de.ibm.com> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
Avi Kivity [Thu, 11 Oct 2007 13:12:24 +0000 (15:12 +0200)]
KVM: MMU: Disable write access on clean large pages
By forcing clean huge pages to be read-only, we have separate roles
for the shadow of a clean large page and the shadow of a dirty large
page. This is necessary because different ptes will be instantiated
for the two cases, even for read faults.
Anthony Liguori [Thu, 11 Oct 2007 01:08:41 +0000 (20:08 -0500)]
KVM: MMU: More struct kvm_vcpu -> struct kvm cleanups
This time, the biggest change is gpa_to_hpa. The translation of GPA to HPA does
not depend on the VCPU state unlike GVA to GPA so there's no need to pass in
the kvm_vcpu.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
Anthony Liguori [Thu, 11 Oct 2007 00:25:50 +0000 (19:25 -0500)]
KVM: MMU: Clean up MMU functions to take struct kvm when appropriate
Some of the MMU functions take a struct kvm_vcpu even though they affect all
VCPUs. This patch cleans up some of them to instead take a struct kvm. This
makes things a bit more clear.
The main thing that was confusing me was whether certain functions need to be
called on all VCPUs.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
Rusty Russell [Mon, 8 Oct 2007 00:48:30 +0000 (10:48 +1000)]
KVM: Add kvm_free_lapic() to pair with kvm_create_lapic()
Instead of the asymetry of kvm_free_apic, implement kvm_free_lapic().
And guess what? I found a minor bug: we don't need to hrtimer_cancel()
from kvm_main.c, because we do that in kvm_free_apic().
Also:
1) kvm_vcpu_uninit should be the reverse order from kvm_vcpu_init.
2) Don't set apic->regs_page to zero before freeing apic.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Avi Kivity <avi@qumranet.com>
KVM: Remove the usage of page->private field by rmap
When kvm uses user-allocated pages in the future for the guest, we won't
be able to use page->private for rmap, since page->rmap is reserved for
the filesystem. So we move the rmap base pointers to the memory slot.
A side effect of this is that we need to store the gfn of each gpte in
the shadow pages, since the memory slot is addressed by gfn, instead of
hfn like struct page.
Signed-off-by: Izik Eidus <izik@qumranet.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
KVM: x86 emulator: remove _eflags and use directly ctxt->eflags.
Remove _eflags and use directly ctxt->eflags. Caching eflags is not needed as
it is restored to vcpu by kvm_main.c:emulate_instruction() from ctxt->eflags
only if emulation doesn't fail.
Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net> Signed-off-by: Avi Kivity <avi@qumranet.com>
Ryan Harper [Tue, 18 Sep 2007 19:05:16 +0000 (14:05 -0500)]
KVM: MMU: Ignore reserved bits in cr3 in non-pae mode
This patch removes the fault injected when the guest attempts to set reserved
bits in cr3. X86 hardware doesn't generate a fault when setting reserved bits.
The result of this patch is that vmware-server, running within a kvm guest,
boots and runs memtest from an iso.
Signed-off-by: Ryan Harper <ryanh@us.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
Avi Kivity [Sun, 23 Sep 2007 12:10:49 +0000 (14:10 +0200)]
KVM: MMU: Make flooding detection work when guest page faults are bypassed
When we allow guest page faults to reach the guests directly, we lose
the fault tracking which allows us to detect demand paging. So we provide
an alternate mechnism by clearing the accessed bit when we set a pte, and
checking it later to see if the guest actually used it.
Avi Kivity [Sun, 16 Sep 2007 16:58:32 +0000 (18:58 +0200)]
KVM: Allow not-present guest page faults to bypass kvm
There are two classes of page faults trapped by kvm:
- host page faults, where the fault is needed to allow kvm to install
the shadow pte or update the guest accessed and dirty bits
- guest page faults, where the guest has faulted and kvm simply injects
the fault back into the guest to handle
The second class, guest page faults, is pure overhead. We can eliminate
some of it on vmx using the following evil trick:
- when we set up a shadow page table entry, if the corresponding guest pte
is not present, set up the shadow pte as not present
- if the guest pte _is_ present, mark the shadow pte as present but also
set one of the reserved bits in the shadow pte
- tell the vmx hardware not to trap faults which have the present bit clear
With this, normal page-not-present faults go directly to the guest,
bypassing kvm entirely.
Unfortunately, this trick only works on Intel hardware, as AMD lacks a
way to discriminate among page faults based on error code. It is also
a little risky since it uses reserved bits which might become unreserved
in the future, so a module parameter is provided to disable it.
Avi Kivity [Wed, 29 Aug 2007 00:48:05 +0000 (03:48 +0300)]
KVM: VMX: Further reduce efer reloads
KVM avoids reloading the efer msr when the difference between the guest
and host values consist of the long mode bits (which are switched by
hardware) and the NX bit (which is emulated by the KVM MMU).
This patch also allows KVM to ignore SCE (syscall enable) when the guest
is running in 32-bit mode. This is because the syscall instruction is
not available in 32-bit mode on Intel processors, so the SCE bit is
effectively meaningless.
Move emulate_ctxt to kvm_vcpu to keep emulate context when we exit from kvm
module. Call x86_decode_insn() only when needed. Modify x86_emulate_insn() to
not modify the context if it must be re-entered.
Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net> Signed-off-by: Avi Kivity <avi@qumranet.com>
KVM: x86 emulator: move all x86_emulate_memop() to a structure
Move all x86_emulate_memop() common variables between decode and execute to a
structure decode_cache. This will help in later separating decode and
emulate.
struct decode_cache {
u8 twobyte;
u8 b;
u8 lock_prefix;
u8 rep_prefix;
u8 op_bytes;
u8 ad_bytes;
struct operand src;
struct operand dst;
unsigned long *override_base;
unsigned int d;
unsigned long regs[NR_VCPU_REGS];
unsigned long eip;
/* modrm */
u8 modrm;
u8 modrm_mod;
u8 modrm_reg;
u8 modrm_rm;
u8 use_modrm_ea;
unsigned long modrm_ea;
unsigned long modrm_val;
};
Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net> Signed-off-by: Avi Kivity <avi@qumranet.com>
Anthony Liguori [Mon, 17 Sep 2007 19:57:50 +0000 (14:57 -0500)]
KVM: Refactor hypercall infrastructure (v3)
This patch refactors the current hypercall infrastructure to better
support live migration and SMP. It eliminates the hypercall page by
trapping the UD exception that would occur if you used the wrong hypercall
instruction for the underlying architecture and replacing it with the right
one lazily.
A fall-out of this patch is that the unhandled hypercalls no longer trap to
userspace. There is very little reason though to use a hypercall to
communicate with userspace as PIO or MMIO can be used. There is no code
in tree that uses userspace hypercalls.
[avi: fix #ud injection on vmx]
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
* git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86: (890 commits)
x86: fix nodemap_size according to nodeid bits
x86: fix overlap between pagetable with bss section
x86: add PCI IDs to k8topology_64.c
x86: fix early_ioremap pagetable ops
x86: use the same pgd_list for PAE and 64-bit
x86: defer cr3 reload when doing pud_clear()
x86: early boot debugging via FireWire (ohci1394_dma=early)
x86: don't special-case pmd allocations as much
x86: shrink some ifdefs in fault.c
x86: ignore spurious faults
x86: remove nx_enabled from fault.c
x86: unify fault_32|64.c
x86: unify fault_32|64.c with ifdefs
x86: unify fault_32|64.c by ifdef'd function bodies
x86: arch/x86/mm/init_32.c printk fixes
x86: arch/x86/mm/init_32.c cleanup
x86: arch/x86/mm/init_64.c printk fixes
x86: unify ioremap
x86: fixes some bugs about EFI memory map handling
x86: use reboot_type on EFI 32
...
Both the old e1000 driver and the new e1000e driver can drive some
PCI-Express e1000 cards, and we should avoid ambiguity about which
driver will pick up the support for those cards when both drivers are
enabled.
This solves the problem by having the old driver support those cards if
the new driver isn't configured, but otherwise ceding support for PCI
Express versions of the e1000 chipset to the newer driver. Thus
allowing both legacy configurations where only the old driver is active
(and handles all chips it knows about) and the new configuration with
the new driver handling the more modern PCIE variants.
Acked-by: Jeff Garzik <jeff@garzik.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus Torvalds [Wed, 30 Jan 2008 13:26:10 +0000 (00:26 +1100)]
Make !NETFILTER_ADVANCED enable IP6_NF_MATCH_IPV6HEADER
We want IPV6HEADER matching for the non-advanced default netfilter
configuration, since it's part of the standard netfilter setup of at
least some distributions (eg Fedora).
Otherwise NETFILTER_ADVANCED loses much of its point, since even
non-advanced users would have to enable all the advanced options just to
get a working IPv6 netfilter setup.
Use a standard list threaded through page->lru for maintaining the pgd
list on PAE. This is the same as 64-bit, and seems saner than using a
non-standard list via page->index.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
PAE mode requires that we reload cr3 in order to guarantee that
changes to the pgd will be noticed by the processor. This means that
in principle pud_clear needs to reload cr3 every time. However,
because reloading cr3 implies a tlb flush, we want to avoid it where
possible.
pud_clear() is only used in a couple of places:
- in free_pmd_range(), when pulling down a range of process address space, and
- huge_pmd_unshare()
In both cases, the calling code will do a a tlb flush anyway, so
there's no need to do it within pud_clear().
In free_pmd_range(), the pud_clear is immediately followed by
pmd_free_tlb(); we can hook that to make the mmu_gather do an
unconditional full flush to make sure cr3 gets reloaded.
In huge_pmd_unshare, it is followed by flush_tlb_range, which always
results in a full cr3-reload tlb flush.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Andi Kleen <ak@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: William Irwin <wli@holomorphy.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Bernhard Kaindl [Wed, 30 Jan 2008 12:34:11 +0000 (13:34 +0100)]
x86: early boot debugging via FireWire (ohci1394_dma=early)
This patch adds a new configuration option, which adds support for a new
early_param which gets checked in arch/x86/kernel/setup_{32,64}.c:setup_arch()
to decide wether OHCI-1394 FireWire controllers should be initialized and
enabled for physical DMA access to allow remote debugging of early problems
like issues ACPI or other subsystems which are executed very early.
If the config option is not enabled, no code is changed, and if the boot
paramenter is not given, no new code is executed, and independent of that,
all new code is freed after boot, so the config option can be even enabled
in standard, non-debug kernels.
With specialized tools, it is then possible to get debugging information
from machines which have no serial ports (notebooks) such as the printk
buffer contents, or any data which can be referenced from global pointers,
if it is stored below the 4GB limit and even memory dumps of of the physical
RAM region below the 4GB limit can be taken without any cooperation from the
CPU of the host, so the machine can be crashed early, it does not matter.
In the extreme, even kernel debuggers can be accessed in this way. I wrote
a small kgdb module and an accompanying gdb stub for FireWire which allows
to gdb to talk to kgdb using remote remory reads and writes over FireWire.
An version of the gdb stub fore FireWire is able to read all global data
from a system which is running a a normal kernel without any kernel debugger,
without any interruption or support of the system's CPU. That way, e.g. the
task struct and so on can be read and even manipulated when the physical DMA
access is granted.
A HOWTO is included in this patch, in Documentation/debugging-via-ohci1394.txt
and I've put a copy online at
ftp://ftp.suse.de/private/bk/firewire/docs/debugging-via-ohci1394.txt
It also has links to all the tools which are available to make use of it
another copy of it is online at:
ftp://ftp.suse.de/private/bk/firewire/kernel/ohci1394_dma_early-v2.diff
Signed-Off-By: Bernhard Kaindl <bk@suse.de> Tested-By: Thomas Renninger <trenn@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In x86 PAE mode, stop treating pmds as a special case. Previously
they were always allocated and freed with the pgd. The modifies the
code to be the same as 64-bit mode, where they are allocated on
demand.
This is a step on the way to unifying 32/64-bit pagetable allocation
as much as possible.
There is a complicating wart, however. When you install a new
reference to a pmd in the pgd, the processor isn't guaranteed to see
it unless you reload cr3. Since reloading cr3 also has the
side-effect of flushing the tlb, this is an expense that we want to
avoid whereever possible.
This patch simply avoids reloading cr3 unless the update is to the
current pagetable. Later patches will optimise this further.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Andi Kleen <ak@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: William Irwin <wli@holomorphy.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When changing a kernel page from RO->RW, it's OK to leave stale TLB
entries around, since doing a global flush is expensive and they pose
no security problem. They can, however, generate a spurious fault,
which we should catch and simply return from (which will have the
side-effect of reloading the TLB to the current PTE).
This can occur when running under Xen, because it frequently changes
kernel pages from RW->RO->RW to implement Xen's pagetable semantics.
It could also occur when using CONFIG_DEBUG_PAGEALLOC, since it avoids
doing a global TLB flush after changing page permissions.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Harvey Harrison [Wed, 30 Jan 2008 12:34:11 +0000 (13:34 +0100)]
x86: remove nx_enabled from fault.c
On !PAE 32-bit, _PAGE_NX will be 0, making is_prefetch always
return early. The test is sufficient on PAE as __supported_pte_mask
is updated in the same places as nx_enabled in init_32.c which also
takes disable_nx into account.
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Ingo Molnar [Wed, 30 Jan 2008 12:34:09 +0000 (13:34 +0100)]
x86: make ioremap() UC by default
Yes! A mere 120 c_p_a() fixing and rewriting patches later,
we are now confident that we can enable UC by default for
ioremap(), on x86 too.
Every other architectures was doing this already. Doing so
makes Linux more robust against MTRR mixups (which might go
unnoticed if BIOS writers test other OSs only - where PAT
might override bad MTRRs defaults).
Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Thomas Gleixner [Wed, 30 Jan 2008 12:34:09 +0000 (13:34 +0100)]
x86: cpa cleanup the 64-bit alias math
Cleanup the address calculations, which are necessary to identify the
high/low alias mappings of the kernel on 64 bit machines. Instead of
calling __pa/__va back and forth, calculate the physical address once
and base the other calculations on it. Add understandable constants so
we can use the already available within() helper. Also add comments,
which help mere mortals to understand what this code does.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Thomas Gleixner [Wed, 30 Jan 2008 12:34:08 +0000 (13:34 +0100)]
x86: cpa: rename global_flush_tlb() to cpa_flush_all()
The function name global_flush_tlb() suggests something different from
what the function really does. Rename it to cpa_flush_all(), which is an
understandable counterpart to cpa_flush_range().
no global visibility of the old API anymore.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Thomas Gleixner [Wed, 30 Jan 2008 12:34:08 +0000 (13:34 +0100)]
x86: cpa: implement clflush optimization
Use clflush on CPUs which support this.
clflush is only used when the page attribute operation has been
successful. On CPUs which do not support clflush and in the case of
error the old fashioned global_flush_tlb() is called.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Thomas Gleixner [Wed, 30 Jan 2008 12:34:08 +0000 (13:34 +0100)]
x86: cpa move the flush into set and clear functions
To avoid the modification of the flush code for the clflush
implementation, move the flush into the set and clear functions and
provide helper functions for the debugging code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Arjan van de Ven [Wed, 30 Jan 2008 12:34:08 +0000 (13:34 +0100)]
x86: add testcases for RODATA and NX protections/attributes
Latest update; I now have 4 NX tests, but 2 fail so they're #if 0'd.
I also cleaned up the NX test code quite a bit, and got rid of the ugly
exception table sorting stuff.
From: Arjan van de Ven <arjan@linux.intel.com>
This patch adds testcases for the CONFIG_DEBUG_RODATA configuration option
as well as the NX CPU feature/mappings. Both testcases can move to tests/
once that patch gets merged into mainline.
(I'm half considering moving the rodata test into mm/init.c but I'll
wait with that until init.c is unified)
As part of this I had to fix a not-quite-right alignment in the vmlinux.lds.h
for the RODATA sections, which lead to 1 page less being marked read only.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Arjan van de Ven [Wed, 30 Jan 2008 12:34:07 +0000 (13:34 +0100)]
x86: fix pageattr-selftest
In Ingo's testing, he found a bug in the CPA selftest code. What would
happen is that the test would call change_page_attr_addr on a range of
memory, part of which was read only, part of which was writable. The
only thing the test wanted to change was the global bit...
What actually happened was that the selftest would take the permissions
of the first page, and then the change_page_attr_addr call would then
set the permissions of the entire range to this first page. In the
rodata section case, this resulted in pages after the .rodata becoming
read only... which made the kernel rather unhappy in many interesting
ways.
This is just another example of how dangerous the cpa API is (was); this
patch changes the test to use the incremental clear/set APIs
instead, and it changes the clear/set implementation to work on a 1 page
at a time basis.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
projects / linux-beck.git / log