On Thu, Jul 10, 2014 at 03:59:43AM -0700, kan.li...@intel.com wrote:
From: Kan Liang kan.li...@intel.com
x86, perf: Protect LBR and extra_regs against KVM lying
With -cpu host, KVM reports LBR and extra_regs support, if the host has
support.
When the guest perf driver tries to access LBR
On Thu, Jul 10, 2014 at 03:59:43AM -0700, kan.li...@intel.com wrote:
+/*
+ * Under certain circumstances, access certain MSR may cause #GP.
+ * The function tests if the input MSR can be safely accessed.
+ */
+static inline bool check_msr(unsigned long msr)
+{
+ u64 val_old, val_new,
Il 10/07/2014 12:59, kan.li...@intel.com ha scritto:
From: Kan Liang kan.li...@intel.com
x86, perf: Protect LBR and extra_regs against KVM lying
With -cpu host, KVM reports LBR and extra_regs support, if the host has support.
When the guest perf driver tries to access LBR or extra_regs MSR,
it
On Mon, Jul 14, 2014 at 01:55:03PM +0200, Paolo Bonzini wrote:
Il 10/07/2014 12:59, kan.li...@intel.com ha scritto:
From: Kan Liang kan.li...@intel.com
x86, perf: Protect LBR and extra_regs against KVM lying
With -cpu host, KVM reports LBR and extra_regs support, if the host has
support.
Il 14/07/2014 14:09, Peter Zijlstra ha scritto:
On Mon, Jul 14, 2014 at 01:55:03PM +0200, Paolo Bonzini wrote:
Il 10/07/2014 12:59, kan.li...@intel.com ha scritto:
From: Kan Liang kan.li...@intel.com
x86, perf: Protect LBR and extra_regs against KVM lying
With -cpu host, KVM reports LBR and
On Mon, Jul 14, 2014 at 02:40:33PM +0200, Paolo Bonzini wrote:
Hmmm, I thought rdmsr_safe was going to return zero, but it just returns
whatever happened to be in edx:eax which maybe should also be fixed.
Kan Liang, what happens if CONFIG_PARAVIRT=y? Do you get garbage or just no
events
For reproducing the issue, please build the kernel with
CONFIG_KVM_INTEL = y (for host kernel).
And CONFIG_PARAVIRT = n and CONFIG_KVM_GUEST = n (for guest
kernel).
I'm not sure this is a useful patch.
This is #GP'ing just because of a limitation in the PMU; just compile
the
Il 14/07/2014 15:36, Liang, Kan ha scritto:
Kan Liang, what happens if CONFIG_PARAVIRT=y? Do you get garbage or
just no events reported?
Guest rdmsr/wrmsr will eventually call rdmsr_safe/wrmsr_safe. They will handle
the #GP. So there is no error report in guest.
Yeah, but what's the
-Original Message-
From: Paolo Bonzini [mailto:pbonz...@redhat.com]
Sent: Monday, July 14, 2014 9:40 AM
To: Liang, Kan; Peter Zijlstra
Cc: a...@firstfloor.org; linux-ker...@vger.kernel.org; kvm@vger.kernel.org
Subject: Re: [PATCH V5 1/2] perf ignore LBR and extra_regs
Il 14/07
Il 14/07/2014 14:48, Peter Zijlstra ha scritto:
In fact there's no reason why LBR cannot be virtualized (though it does need
support from the processor), and it may even be possible to support
OFFCORE_RSP_X in the KVM virtual PMU.
But its not, so something needs to be done, right?
A first
diff --git a/arch/x86/kernel/cpu/perf_event.h
b/arch/x86/kernel/cpu/perf_event.h
index 3b2f9bd..992c678 100644
--- a/arch/x86/kernel/cpu/perf_event.h
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -464,6 +464,12 @@ struct x86_pmu {
*/
struct extra_reg *extra_regs;
so once more; and then I'm going to route your emails to /dev/null, wrap
text at 78 chars.
On Mon, Jul 14, 2014 at 02:28:36PM +, Liang, Kan wrote:
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -464,6 +464,12 @@ struct x86_pmu {
*/
struct extra_reg *extra_regs;
unsigned int
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