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| author |   Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2018-04-25 22:04:19 -0400 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2018-05-03 13:55:47 +0200 |
| commit | 5cf687548705412da47c9cec342fd952d71ed3d5 (patch) | |
| tree | 5b868ec35064f655e390b04a8ff520af0a660e7e /Documentation | |
| parent | x86/bugs: Read SPEC_CTRL MSR during boot and re-use reserved bits (diff) | |
| download | linux-dev-5cf687548705412da47c9cec342fd952d71ed3d5.tar.xz linux-dev-5cf687548705412da47c9cec342fd952d71ed3d5.zip | |
x86/bugs, KVM: Support the combination of guest and host IBRS
A guest may modify the SPEC_CTRL MSR from the value used by the
kernel. Since the kernel doesn't use IBRS, this means a value of zero is
what is needed in the host.
But the 336996-Speculative-Execution-Side-Channel-Mitigations.pdf refers to
the other bits as reserved so the kernel should respect the boot time
SPEC_CTRL value and use that.
This allows to deal with future extensions to the SPEC_CTRL interface if
any at all.
Note: This uses wrmsrl() instead of native_wrmsl(). I does not make any
difference as paravirt will over-write the callq *0xfff.. with the wrmsrl
assembler code.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation')
0 files changed, 0 insertions, 0 deletions