From: Kyle Huey <me@kylehuey.com>
To: "Robert O'Callahan" <robert@ocallahan.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Andy Lutomirski" <luto@kernel.org>,
"Ingo Molnar" <mingo@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, "Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Jeff Dike" <jdike@addtoit.com>,
"Richard Weinberger" <richard@nod.at>,
"Alexander Viro" <viro@zeniv.linux.org.uk>,
"Shuah Khan" <shuah@kernel.org>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Borislav Petkov" <bp@suse.de>,
"Peter Zijlstra" <peterz@infradead.org>,
"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
"Len Brown" <len.brown@intel.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
"Dmitry Safonov" <dsafonov@virtuozzo.com>
Cc: linux-kernel@vger.kernel.org,
user-mode-linux-devel@lists.sourceforge.net,
user-mode-linux-user@lists.sourceforge.net,
linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org,
kvm@vger.kernel.org
Subject: [PATCH v8 0/7] x86/arch_prctl Add ARCH_[GET|SET]_CPUID for controlling the CPUID instruction
Date: Mon, 31 Oct 2016 18:37:42 -0700 [thread overview]
Message-ID: <20161101013749.4003-1-khuey@kylehuey.com> (raw)
rr (http://rr-project.org/), a userspace record-and-replay reverse-
execution debugger, would like to trap and emulate the CPUID instruction.
This would allow us to a) mask away certain hardware features that rr does
not support (e.g. RDRAND) and b) enable trace portability across machines
by providing constant results.
Newer Intel CPUs (Ivy Bridge and later) can fault when CPUID is executed at
CPL > 0. Expose this capability to userspace as a new pair of arch_prctls,
ARCH_GET_CPUID and ARCH_SET_CPUID, with two values, ARCH_CPUID_ENABLE and
ARCH_CPUID_SIGSEGV.
Since v7:
Patch 5:
- Applied and tested Thomas's review comments re: generic MSR testing code.
Patch 6:
- arch_prctl now returns ENODEV for ARCH_[GET|SET]_CPUID if the feature
is not supported by the hardware. The selftest has been updated for this.
- Applied and tested review comments from Thomas and Andy re: context
switching performance.
Added patch 7, implementing KVM support for virtualizing cpuid faulting.
One thing to note is that this exposes this Intel-only feature to VMs
running on both Intel and AMD CPUs. A Linux guest kernel with these patches
will not take advantage of this on an AMD CPU though, because the feature
detection code inside Linux is in an Intel-specific codepath.
next reply other threads:[~2016-11-01 1:37 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-01 1:37 Kyle Huey [this message]
2016-11-01 1:37 ` [PATCH v8 1/7] x86/arch_prctl/64: Use SYSCALL_DEFINE2 to define sys_arch_prctl Kyle Huey
2016-11-01 1:37 ` [PATCH v8 2/7] x86/arch_prctl/64: Rename do_arch_prctl to do_arch_prctl_64 Kyle Huey
2016-11-01 1:37 ` [PATCH v8 3/7] x86/arch_prctl: Add do_arch_prctl_common Kyle Huey
2016-11-01 1:37 ` [PATCH v8 4/7] x86/syscalls/32: Wire up arch_prctl on x86-32 Kyle Huey
2016-11-01 1:37 ` [PATCH v8 5/7] x86/cpufeature: Detect CPUID faulting support Kyle Huey
2016-11-01 1:37 ` [PATCH v8 6/7] x86/arch_prctl: Add ARCH_[GET|SET]_CPUID Kyle Huey
2016-11-01 1:37 ` [PATCH v8 7/7] KVM: x86: virtualize cpuid faulting Kyle Huey
2016-11-01 14:26 ` Paolo Bonzini
2016-11-01 18:33 ` Thomas Gleixner
2016-11-01 22:51 ` Paolo Bonzini
2016-11-04 20:34 ` David Matlack
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