From: Borislav Petkov <bp@alien8.de>
To: Paolo Bonzini <pbonzini@redhat.com>,
Eduardo Habkost <ehabkost@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX
Date: Thu, 7 Jul 2016 12:41:28 +0200 [thread overview]
Message-ID: <20160707104128.GC13648@pd.tnic> (raw)
In-Reply-To: <361b792f-87ce-863d-5098-9a18aadd6379@redhat.com>
On Wed, Jul 06, 2016 at 04:29:35PM +0200, Paolo Bonzini wrote:
> Can you test this in the meanwhile:
>
> git clone git://git.kernel.org/pub/scm/virt/kvm/kvm-unit-tests.git
> cd kvm-unit-tests
> ./configure
> make
> ./x86/run x86/tsc.flat -cpu kvm64,+rdtscp
>
> On Intel I see:
>
> enabling apic
> rdtsc latency 18
> rdtsc after wrtsc(0): 727124155
> rdtsc after wrtsc(100000000000): 100000001759
> PASS: Test RDTSCP 0
> PASS: Test RDTSCP 10
> PASS: Test RDTSCP 256
> SUMMARY: 3 tests
Ok, found it: I need to start the guest with "+rdtscp", see below.
Which begs the question: can we readd CPUID_EXT2_RDTSCP to the Opteron_*
models as in the second diff here:
https://lkml.kernel.org/r/20160706124438.GB7300@pd.tnic
?
Or are we still afraid of "host doesn't support requested feature"
messages from:
33b5e8c03ae7 ("target-i386: Disable rdtscp on Opteron_G* CPU models")
?
$ ./x86/run x86/tsc.flat -cpu kvm64,+rdtscp
qemu-system-x86_64 -enable-kvm -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -kernel x86/tsc.flat -cpu kvm64,+rdtscp
enabling apic
rdtsc latency 68
rdtsc after wrtsc(0): 988590164
rdtsc after wrtsc(100000000000): 100000002807
PASS: Test RDTSCP 0
PASS: Test RDTSCP 10
PASS: Test RDTSCP 256
SUMMARY: 3 tests
latest qemu:
$ QEMU=/root/src/qemu/qemu.git/x86_64-softmmu/qemu-system-x86_64 ./x86/run x86/tsc.flat -cpu kvm64,+rdtscp
/root/src/qemu/qemu.git/x86_64-softmmu/qemu-system-x86_64 -enable-kvm -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -kernel x86/tsc.flat -cpu kvm64,+rdtscp
enabling apic
rdtsc latency 69
rdtsc after wrtsc(0): 715310314
rdtsc after wrtsc(100000000000): 100000002434
PASS: Test RDTSCP 0
PASS: Test RDTSCP 10
PASS: Test RDTSCP 256
SUMMARY: 3 tests
guest booted *without* "+rdtscp":
taskset -c 3 ./rdtscp
aux1: 0x0
aux2: 0x0
p1: 284683839780, p2: 284684080314, 240534
with "+rdtscp":
$ taskset -c 3 ./rdtscp
aux1: 0x3
aux2: 0x3
p1: 168907589830, p2: 168907856068, 266238
$ taskset -c 2 ./rdtscp
aux1: 0x2
aux2: 0x2
p1: 176251144121, p2: 176251427089, 282968
Ok, all good.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
next prev parent reply other threads:[~2016-07-07 10:41 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-06 13:43 [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Paolo Bonzini
2016-07-06 14:18 ` Borislav Petkov
2016-07-06 14:29 ` Paolo Bonzini
2016-07-07 10:41 ` Borislav Petkov [this message]
2016-07-07 11:01 ` Paolo Bonzini
2016-07-07 11:47 ` Borislav Petkov
2016-07-07 12:28 ` Paolo Bonzini
2016-07-07 12:47 ` Borislav Petkov
2016-07-07 13:16 ` Paolo Bonzini
2016-07-07 16:01 ` Borislav Petkov
2016-07-07 16:17 ` Paolo Bonzini
2016-07-07 16:27 ` Eduardo Habkost
2016-07-07 17:04 ` Borislav Petkov
2016-07-07 17:43 ` Eduardo Habkost
2016-07-08 11:09 ` Borislav Petkov
2016-07-08 11:15 ` Paolo Bonzini
2016-07-08 12:55 ` Borislav Petkov
2016-07-06 15:00 ` kbuild test robot
2016-07-15 12:15 ` Radim Krčmář
2016-07-15 12:30 ` Paolo Bonzini
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