From: Paolo Bonzini <pbonzini@redhat.com>
To: Eduardo Habkost <ehabkost@redhat.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"Kang, Luwei" <luwei.kang@intel.com>,
"Strong, Beeman" <beeman.strong@intel.com>,
"rth@twiddle.net" <rth@twiddle.net>
Subject: Re: [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel PT
Date: Fri, 25 Sep 2020 22:40:34 +0200 [thread overview]
Message-ID: <db31a0fa-c6cf-4730-6d64-f81228948d30@redhat.com> (raw)
In-Reply-To: <20200925202956.GV3717385@habkost.net>
On 25/09/20 22:29, Eduardo Habkost wrote:
>> No, it's not possible. KVM doesn't have a say on what the processor
>> writes in the tracing packets.
> Can KVM refuse to enable packet generation if CSbase is not zero
> and CPUID.(EAX=14H,ECX=0)[bit 31] seen by guest is different from
> host?
Yes, but the processor could change operating mode (and hence CSbase)
while tracing is active. This is very unlikely, since it would require
nonzero CS-base and a 32-bit host, but in principle not impossible
(could be a firmware call, for example).
The only solution is for KVM to accept both, and for QEMU to refuse a
setting that does not match the host.
Paolo
next prev parent reply other threads:[~2020-09-25 20:41 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-24 21:38 [PATCH v1 0/3] Remove the limitation of Intel PT CPUID info Luwei Kang
2020-02-24 21:38 ` [PATCH v1 1/3] i386: Remove the limitation of IP payloads for Intel PT Luwei Kang
2020-09-25 16:15 ` Eduardo Habkost
2020-09-25 16:42 ` Strong, Beeman
2020-09-25 16:54 ` Eduardo Habkost
2020-09-25 20:23 ` Paolo Bonzini
2020-09-25 20:29 ` Eduardo Habkost
2020-09-25 20:40 ` Paolo Bonzini [this message]
2020-09-28 5:19 ` Kang, Luwei
2020-09-28 7:35 ` Paolo Bonzini
2020-09-28 12:42 ` Kang, Luwei
2020-09-28 14:12 ` Eduardo Habkost
2020-09-29 2:28 ` Kang, Luwei
2020-09-29 3:44 ` Eduardo Habkost
2020-09-28 16:46 ` Paolo Bonzini
2020-09-29 2:28 ` Kang, Luwei
2020-02-24 21:38 ` [PATCH v1 2/3] i386: Remove the CPUID limitation of " Luwei Kang
2020-02-24 21:38 ` [PATCH v1 3/3] i386: Mark the 'INTEL_PT' CPUID bit as unmigratable Luwei Kang
2020-03-30 9:56 ` [PATCH v1 0/3] Remove the limitation of Intel PT CPUID info Kang, Luwei
2020-09-18 22:02 ` Eduardo Habkost
2020-09-21 7:49 ` Kang, Luwei
2020-09-21 16:50 ` Eduardo Habkost
2020-09-23 2:52 ` Kang, Luwei
2020-09-23 14:15 ` Eduardo Habkost
2020-09-24 12:47 ` Kang, Luwei
2020-09-24 13:34 ` Eduardo Habkost
2020-09-25 8:20 ` Kang, Luwei
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=db31a0fa-c6cf-4730-6d64-f81228948d30@redhat.com \
--to=pbonzini@redhat.com \
--cc=beeman.strong@intel.com \
--cc=ehabkost@redhat.com \
--cc=luwei.kang@intel.com \
--cc=qemu-devel@nongnu.org \
--cc=rth@twiddle.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).