The MPX code appears is calling a low-level FPU function
(copy_fpregs_to_fpstate()). This function is not able to
be called in all contexts, although it is safe to call
directly in some cases.
Although probably correct, the current code is ugly and
potentially error-prone. So, add a wrapper that calls
the (slightly) higher-level fpu__save() (which is preempt-
safe) and also ensures that we even *have* an FPU context
(in the case that this was called when in lazy FPU mode).
Ingo had this to say about the details about when we need
preemption disabled:
> it's indeed generally unsafe to access/copy FPU registers with preemption enabled,
> for two reasons:
>
> - on older systems that use FSAVE the instruction destroys FPU register
> contents, which has to be handled carefully
>
> - even on newer systems if we copy to FPU registers (which this code doesn't)
> then we don't want a context switch to occur in the middle of it, because a
> context switch will write to the fpstate, potentially overwriting our new data
> with old FPU state.
>
> But it's safe to access FPU registers with preemption enabled in a couple of
> special cases:
>
> - potentially destructively saving FPU registers: the signal handling code does
> this in copy_fpstate_to_sigframe(), because it can rely on the signal restore
> side to restore the original FPU state.
>
> - reading FPU registers on modern systems: we don't do this anywhere at the
> moment, mostly to keep symmetry with older systems where FSAVE is
> destructive.
>
> - initializing FPU registers on modern systems: fpu__clear() does this. Here
> it's safe because we don't copy from the fpstate.
>
> - directly writing FPU registers from user-space memory (!). We do this in
> fpu__restore_sig(), and it's safe because neither context switches nor
> irq-handler FPU use can corrupt the source context of the copy (which is
> user-space memory).
>
> Note that the MPX code's current use of copy_fpregs_to_fpstate() was safe I think,
> because:
>
> - MPX is predicated on eagerfpu, so the destructive F[N]SAVE instruction won't be
> used.
>
> - the code was only reading FPU registers, and was doing it only in places that
> guaranteed that an FPU state was already active (i.e. didn't do it in
> kthreads)
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave@sr71.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Cc: bp@alien8.de
Link: http://lkml.kernel.org/r/20150607183700.AA881696@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This fixes up a merge issue with the amba-pl011.c driver, and we want
the fixes in this branch as well.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pci_dma_burst_advice() was added by e24c2d963a ("[PATCH] PCI: DMA
bursting advice") but apparently never used. Remove it.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Michal Simek <monstr@monstr.eu> # microblaze
CC: David S. Miller <davem@davemloft.net>
The 'system_call' entry points differ starkly between native 32-bit and 64-bit
kernels: on 32-bit kernels it defines the INT 0x80 entry point, while on
64-bit it's the SYSCALL entry point.
This is pretty confusing when looking at generic code, and it also obscures
the nature of the entry point at the assembly level.
So unangle this by splitting the name into its two uses:
system_call (32) -> entry_INT80_32
system_call (64) -> entry_SYSCALL_64
As per the generic naming scheme for x86 system call entry points:
entry_MNEMONIC_qualifier
where 'qualifier' is one of _32, _64 or _compat.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So the SYSENTER instruction is pretty quirky and it has different behavior
depending on bitness and CPU maker.
Yet we create a false sense of coherency by naming it 'ia32_sysenter_target'
in both of the cases.
Split the name into its two uses:
ia32_sysenter_target (32) -> entry_SYSENTER_32
ia32_sysenter_target (64) -> entry_SYSENTER_compat
As per the generic naming scheme for x86 system call entry points:
entry_MNEMONIC_qualifier
where 'qualifier' is one of _32, _64 or _compat.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
... and we're done. :)
Because SMBASE is usually relocated above 1M on modern chipsets, and
SMM handlers might indeed rely on 4G segment limits, we only expose it
if KVM is able to run the guest in big real mode. This includes any
of VMX+emulate_invalid_guest_state, VMX+unrestricted_guest, or SVM.
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This is now very simple to do. The only interesting part is a simple
trick to find the right memslot in gfn_to_rmap, retrieving the address
space from the spte role word. The same trick is used in the auditing
code.
The comment on top of union kvm_mmu_page_role has been stale forever,
so remove it. Speaking of stale code, remove pad_for_nice_hex_output
too: it was splitting the "access" bitfield across two bytes and thus
had effectively turned into pad_for_ugly_hex_output.
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This patch has no semantic change, but it prepares for the introduction
of a second address space for system management mode.
A new function x86_set_memory_region (and the "slots_lock taken"
counterpart __x86_set_memory_region) is introduced in order to
operate on all address spaces when adding or deleting private
memory slots.
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We need to hide SMRAM from guests not running in SMM. Therefore,
all uses of kvm_read_guest* and kvm_write_guest* must be changed to
check whether the VCPU is in system management mode and use a
different set of memslots. Switch from kvm_* to the newly-introduced
kvm_vcpu_*, which call into kvm_arch_vcpu_memslots_id.
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This patch adds the interface between x86.c and the emulator: the
SMBASE register, a new emulator flag, the RSM instruction. It also
adds a new request bit that will be used by the KVM_SMI ioctl.
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This patch includes changes to the external API for SMM support.
Userspace can predicate the availability of the new fields and
ioctls on a new capability, KVM_CAP_X86_SMM, which is added at the end
of the patch series.
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The hflags field will contain information about system management mode
and will be useful for the emulator. Pass the entire field rather than
just the guest-mode information.
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
SMBASE is only readable from SMM for the VCPU, but it must be always
accessible if userspace is accessing it. Thus, all functions that
read MSRs are changed to accept a struct msr_data; the host_initiated
and index fields are pre-initialized, while the data field is filled
on return.
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The early_idt_handlers asm code generates an array of entry
points spaced nine bytes apart. It's not really clear from that
code or from the places that reference it what's going on, and
the code only works in the first place because GAS never
generates two-byte JMP instructions when jumping to global
labels.
Clean up the code to generate the correct array stride (member size)
explicitly. This should be considerably more robust against
screw-ups, as GAS will warn if a .fill directive has a negative
count. Using '. =' to advance would have been even more robust
(it would generate an actual error if it tried to move
backwards), but it would pad with nulls, confusing anyone who
tries to disassemble the code. The new scheme should be much
clearer to future readers.
While we're at it, improve the comments and rename the array and
common code.
Binutils may start relaxing jumps to non-weak labels. If so,
this change will fix our build, and we may need to backport this
change.
Before, on x86_64:
0000000000000000 <early_idt_handlers>:
0: 6a 00 pushq $0x0
2: 6a 00 pushq $0x0
4: e9 00 00 00 00 jmpq 9 <early_idt_handlers+0x9>
5: R_X86_64_PC32 early_idt_handler-0x4
...
48: 66 90 xchg %ax,%ax
4a: 6a 08 pushq $0x8
4c: e9 00 00 00 00 jmpq 51 <early_idt_handlers+0x51>
4d: R_X86_64_PC32 early_idt_handler-0x4
...
117: 6a 00 pushq $0x0
119: 6a 1f pushq $0x1f
11b: e9 00 00 00 00 jmpq 120 <early_idt_handler>
11c: R_X86_64_PC32 early_idt_handler-0x4
After:
0000000000000000 <early_idt_handler_array>:
0: 6a 00 pushq $0x0
2: 6a 00 pushq $0x0
4: e9 14 01 00 00 jmpq 11d <early_idt_handler_common>
...
48: 6a 08 pushq $0x8
4a: e9 d1 00 00 00 jmpq 120 <early_idt_handler_common>
4f: cc int3
50: cc int3
...
117: 6a 00 pushq $0x0
119: 6a 1f pushq $0x1f
11b: eb 03 jmp 120 <early_idt_handler_common>
11d: cc int3
11e: cc int3
11f: cc int3
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Binutils <binutils@sourceware.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H.J. Lu <hjl.tools@gmail.com>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/ac027962af343b0c599cbfcf50b945ad2ef3d7a8.1432336324.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So the dwarf2 annotations in low level assembly code have
become an increasing hindrance: unreadable, messy macros
mixed into some of the most security sensitive code paths
of the Linux kernel.
These debug info annotations don't even buy the upstream
kernel anything: dwarf driven stack unwinding has caused
problems in the past so it's out of tree, and the upstream
kernel only uses the much more robust framepointers based
stack unwinding method.
In addition to that there's a steady, slow bitrot going
on with these annotations, requiring frequent fixups.
There's no tooling and no functionality upstream that
keeps it correct.
So burn down the sick forest, allowing new, healthier growth:
27 files changed, 350 insertions(+), 1101 deletions(-)
Someone who has the willingness and time to do this
properly can attempt to reintroduce dwarf debuginfo in x86
assembly code plus dwarf unwinding from first principles,
with the following conditions:
- it should be maximally readable, and maximally low-key to
'ordinary' code reading and maintenance.
- find a build time method to insert dwarf annotations
automatically in the most common cases, for pop/push
instructions that manipulate the stack pointer. This could
be done for example via a preprocessing step that just
looks for common patterns - plus special annotations for
the few cases where we want to depart from the default.
We have hundreds of CFI annotations, so automating most of
that makes sense.
- it should come with build tooling checks that ensure that
CFI annotations are sensible. We've seen such efforts from
the framepointer side, and there's no reason it couldn't be
done on the dwarf side.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Setting sched clock stable for kvmclock causes the printk timestamps
to not start from zero, which is different from baremetal and
can possibly break userspace. Add a flag to indicate that
hypervisor sets clock base at zero when kvmclock is initialized.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This lets the function access the new memory slot without going through
kvm_memslots and id_to_memslot. It will simplify the code when more
than one address space will be supported.
Unfortunately, the "const"ness of the new argument must be casted
away in two places. Fixing KVM to accept const struct kvm_memory_slot
pointers would require modifications in pretty much all architectures,
and is left for later.
Reviewed-by: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We use pat_enabled in x86-specific code to see if PAT is enabled
or not but we're granting full access to it even though readers
do not need to set it. If, for instance, we granted access to it
to modules later they then could override the variable
setting... no bueno.
This renames pat_enabled to a new static variable __pat_enabled.
Folks are redirected to use pat_enabled() now.
Code that sets this can only be internal to pat.c. Apart from
the early kernel parameter "nopat" to disable PAT, we also have
a few cases that disable it later and make use of a helper
pat_disable(). It is wrapped under an ifdef but since that code
cannot run unless PAT was enabled its not required to wrap it
with ifdefs, unwrap that. Likewise, since "nopat" doesn't really
change non-PAT systems just remove that ifdef as well.
Although we could add and use an early_param_off(), these
helpers don't use __read_mostly but we want to keep
__read_mostly for __pat_enabled as this is a hot path -- upon
boot, for instance, a simple guest may see ~4k accesses to
pat_enabled(). Since __read_mostly early boot params are not
that common we don't add a helper for them just yet.
Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Walls <awalls@md.metrocast.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kyle McMartin <kyle@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1430425520-22275-3-git-send-email-mcgrof@do-not-panic.com
Link: http://lkml.kernel.org/r/1432628901-18044-13-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
'mtrr_state.enabled' contains the FE (fixed MTRRs enabled)
and E (MTRRs enabled) flags in MSR_MTRRdefType. Intel SDM,
section 11.11.2.1, defines these flags as follows:
- All MTRRs are disabled when the E flag is clear.
The FE flag has no affect when the E flag is clear.
- The default type is enabled when the E flag is set.
- MTRR variable ranges are enabled when the E flag is set.
- MTRR fixed ranges are enabled when both E and FE flags
are set.
MTRR state checks in __mtrr_type_lookup() do not match with SDM.
Hence, this patch makes the following changes:
- The current code detects MTRRs disabled when both E and
FE flags are clear in mtrr_state.enabled. Fix to detect
MTRRs disabled when the E flag is clear.
- The current code does not check if the FE bit is set in
mtrr_state.enabled when looking at the fixed entries.
Fix to check the FE flag.
- The current code returns the default type when the E flag
is clear in mtrr_state.enabled. However, the default type
is UC when the E flag is clear. Remove the code as this
case is handled as MTRR disabled with the 1st change.
In addition, this patch defines the E and FE flags in
mtrr_state.enabled as follows.
- FE flag: MTRR_STATE_MTRR_FIXED_ENABLED
- E flag: MTRR_STATE_MTRR_ENABLED
print_mtrr_state() and x86_get_mtrr_mem_range() are also updated
accordingly.
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Elliott@hp.com
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave.hansen@intel.com
Cc: linux-mm <linux-mm@kvack.org>
Cc: pebolle@tiscali.nl
Link: http://lkml.kernel.org/r/1431714237-880-4-git-send-email-toshi.kani@hp.com
Link: http://lkml.kernel.org/r/1432628901-18044-4-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>