linux-toradex.git/arch/x86/include/asm/kvm_emulate.h, branch v3.2.51

KVM: x86: fix missing checks in syscall emulation

2012-04-02T16:52:49+00:00

commit c2226fc9e87ba3da060e47333657cd6616652b84 upstream.

On hosts without this patch, 32bit guests will crash (and 64bit guests
may behave in a wrong way) for example by simply executing following
nasm-demo-application:

    [bits 32]
    global _start
    SECTION .text
    _start: syscall

(I tested it with winxp and linux - both always crashed)

    Disassembly of section .text:

    00000000 <_start>:
       0:   0f 05                   syscall

The reason seems a missing "invalid opcode"-trap (int6) for the
syscall opcode "0f05", which is not available on Intel CPUs
within non-longmodes, as also on some AMD CPUs within legacy-mode.
(depending on CPU vendor, MSR_EFER and cpuid)

Because previous mentioned OSs may not engage corresponding
syscall target-registers (STAR, LSTAR, CSTAR), they remain
NULL and (non trapping) syscalls are leading to multiple
faults and finally crashs.

Depending on the architecture (AMD or Intel) pretended by
guests, various checks according to vendor's documentation
are implemented to overcome the current issue and behave
like the CPUs physical counterparts.

[mtosatti: cleanup/beautify code]

Signed-off-by: Stephan Baerwolf 
Signed-off-by: Marcelo Tosatti 
Signed-off-by: Stefan Bader 
Signed-off-by: Greg Kroah-Hartman

KVM: x86: extend "struct x86_emulate_ops" with "get_cpuid"

2012-04-02T16:52:49+00:00

commit bdb42f5afebe208eae90406959383856ae2caf2b upstream.

In order to be able to proceed checks on CPU-specific properties
within the emulator, function "get_cpuid" is introduced.
With "get_cpuid" it is possible to virtually call the guests
"cpuid"-opcode without changing the VM's context.

[mtosatti: cleanup/beautify code]

Signed-off-by: Stephan Baerwolf 
Signed-off-by: Marcelo Tosatti 
Signed-off-by: Stefan Bader 
Signed-off-by: Greg Kroah-Hartman

KVM: x86 emulator: expand decode flags to 64 bits

2011-09-25T16:52:49+00:00

Unifiying the operands means not taking advantage of the fact that some
operand types can only go into certain operands (for example, DI can only
be used by the destination), so we need more bits to hold the operand type.

Signed-off-by: Avi Kivity 
Signed-off-by: Marcelo Tosatti

KVM: x86 emulator: move memop, memopp into emulation context

2011-09-25T16:52:47+00:00

Simplifies further generalization of decode.

Signed-off-by: Avi Kivity 
Signed-off-by: Marcelo Tosatti

KVM: x86 emulator: fold decode_cache into x86_emulate_ctxt

2011-07-12T10:16:09+00:00

This saves a lot of pointless casts x86_emulate_ctxt and decode_cache.

Signed-off-by: Avi Kivity 
Signed-off-by: Marcelo Tosatti

KVM: x86 emulator: rename decode_cache::eip to _eip

2011-07-12T10:16:09+00:00

The name eip conflicts with a field of the same name in x86_emulate_ctxt,
which we plan to fold decode_cache into.

The name _eip is unfortunate, but what's really needed is a refactoring
here, not a better name.

Signed-off-by: Avi Kivity 
Signed-off-by: Marcelo Tosatti

KVM: x86 emulator: Avoid clearing the whole decode_cache

2011-07-12T08:45:09+00:00

During tracing the emulator, we noticed that init_emulate_ctxt()
sometimes took a bit longer time than we expected.

This patch is for mitigating the problem by some degree.

By looking into the function, we soon notice that it clears the whole
decode_cache whose size is about 2.5K bytes now.  Furthermore, most of
the bytes are taken for the two read_cache arrays, which are used only
by a few instructions.

Considering the fact that we are not assuming the cache arrays have
been cleared when we store actual data, we do not need to clear the
arrays: 2K bytes elimination.  In addition, we can avoid clearing the
fetch_cache and regs arrays.

This patch changes the initialization not to clear the arrays.

On our 64-bit host, init_emulate_ctxt() becomes 0.3 to 0.5us faster with
this patch applied.

Signed-off-by: Takuya Yoshikawa 
Cc: Gleb Natapov 
Signed-off-by: Avi Kivity

KVM: x86 emulator: Stop passing ctxt->ops as arg of emul functions

2011-07-12T08:44:59+00:00

Dereference it in the actual users.

This not only cleans up the emulator but also makes it easy to convert
the old emulation functions to the new em_xxx() form later.

Note: Remove some inline keywords to let the compiler decide inlining.

Signed-off-by: Takuya Yoshikawa 
Signed-off-by: Marcelo Tosatti

KVM: x86 emulator: consolidate segment accessors

2011-05-22T12:47:39+00:00

Instead of separate accessors for the segment selector and cached descriptor,
use one accessor for both.  This simplifies the code somewhat.

Signed-off-by: Avi Kivity

KVM: SVM: Get rid of x86_intercept_map::valid

2011-05-22T12:39:37+00:00

By reserving 0 as an invalid x86_intercept_stage, we no longer
need to store a valid flag in x86_intercept_map.

Signed-off-by: Avi Kivity