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Filename Latest commit message Latest commit date
Lai Jiangshan 22257d3c68 KVM: X86: Disable hardware breakpoints unconditionally before kvm_x86->run()
commit f85d40160691881a17a397c448d799dfc90987ba upstream.

When the host is using debug registers but the guest is not using them
nor is the guest in guest-debug state, the kvm code does not reset
the host debug registers before kvm_x86->run().  Rather, it relies on
the hardware vmentry instruction to automatically reset the dr7 registers
which ensures that the host breakpoints do not affect the guest.

This however violates the non-instrumentable nature around VM entry
and exit; for example, when a host breakpoint is set on vcpu->arch.cr2,

Another issue is consistency.  When the guest debug registers are active,
the host breakpoints are reset before kvm_x86->run(). But when the
guest debug registers are inactive, the host breakpoints are delayed to
be disabled.  The host tracing tools may see different results depending
on what the guest is doing.

To fix the problems, we clear %db7 unconditionally before kvm_x86->run()
if the host has set any breakpoints, no matter if the guest is using
them or not.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20210628172632.81029-1-jiangshanlai@gmail.com>
Cc: stable@vger.kernel.org
[Only clear %db7 instead of reloading all debug registers. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-07-20 16:10:40 +02:00
arch KVM: X86: Disable hardware breakpoints unconditionally before kvm_x86->run() 2021-07-20 16:10:40 +02:00
block
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drivers pinctrl: mcp23s08: Fix missing unlock on error in mcp23s08_irq() 2021-07-19 08:53:18 +02:00
fs jfs: fix GPF in diFree 2021-07-19 08:53:18 +02:00
include media: subdev: disallow ioctl for saa6588/davinci 2021-07-19 08:53:17 +02:00
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kernel tracing: Resize tgid_map to pid_max, not PID_MAX_DEFAULT 2021-07-19 08:53:17 +02:00
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security smackfs: restrict bytes count in smk_set_cipso() 2021-07-19 08:53:18 +02:00
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virt KVM: mmio: Fix use-after-free Read in kvm_vm_ioctl_unregister_coalesced_mmio 2021-07-20 16:10:40 +02:00
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Makefile Linux 5.4.133 2021-07-19 08:53:18 +02:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.