From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Joerg Roedel" <joro@8bytes.org>,
"Jim Mattson" <jmattson@google.com>
Subject: [PATCH RFC 0/5] x86/KVM/svm: get rid of hardcoded instructions lengths
Date: Thu, 20 Jun 2019 13:02:35 +0200 [thread overview]
Message-ID: <20190620110240.25799-1-vkuznets@redhat.com> (raw)
Jim rightfully complains that hardcoding instuctions lengths is not always
correct: additional (redundant) prefixes can be used. Luckily, the ugliness
is mostly harmless: modern AMD CPUs support NRIP_SAVE feature but I'd like
to clean things up and sacrifice speed in favor of correctness.
Early RFC. Unfortunately, I got distracted by some other problems so
sending it out half-baked.
TODO:
- Get rid of hardcoded '+ 3' in vmrun_interception().
- Test.
P.S. If you'd like to test the series you'll have to have a CPU without
NRIP_SAVE feature or forcefully disable it, something like:
index 8d4e50428b68..93c7eaad7915 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -922,6 +922,9 @@ static void init_amd(struct cpuinfo_x86 *c)
/* AMD CPUs don't reset SS attributes on SYSRET, Xen does. */
if (!cpu_has(c, X86_FEATURE_XENPV))
set_cpu_bug(c, X86_BUG_SYSRET_SS_ATTRS);
+
+ /* No nrips */
+ clear_cpu_cap(c, X86_FEATURE_NRIPS);
}
#ifdef CONFIG_X86_32
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 5beca1030c9a..5b2ea34bc9f2 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -773,11 +773,11 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
- if (svm->vmcb->control.next_rip != 0) {
+/* if (svm->vmcb->control.next_rip != 0) {
WARN_ON_ONCE(!static_cpu_has(X86_FEATURE_NRIPS));
svm->next_rip = svm->vmcb->control.next_rip;
}
-
+*/
if (!svm->next_rip) {
if (kvm_emulate_instruction(vcpu, EMULTYPE_SKIP) !=
EMULATE_DONE)
Vitaly Kuznetsov (5):
x86: KVM: svm: don't pretend to advance RIP in case
wrmsr_interception() results in #GP
x86: KVM: svm: avoid flooding logs when skip_emulated_instruction()
fails
x86: KVM: svm: clear interrupt shadow on all paths in
skip_emulated_instruction()
x86: KVM: add xsetbv to the emulator
x86: KVM: svm: remove hardcoded instruction length from intercepts
arch/x86/include/asm/kvm_emulate.h | 1 +
arch/x86/kvm/emulate.c | 9 ++++++++-
arch/x86/kvm/svm.c | 19 ++++++-------------
3 files changed, 15 insertions(+), 14 deletions(-)
--
2.20.1
next reply other threads:[~2019-06-20 11:02 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-20 11:02 Vitaly Kuznetsov [this message]
2019-06-20 11:02 ` [PATCH RFC 1/5] x86: KVM: svm: don't pretend to advance RIP in case wrmsr_interception() results in #GP Vitaly Kuznetsov
2019-06-20 18:49 ` Jim Mattson
2019-06-21 8:42 ` Vitaly Kuznetsov
2019-06-20 11:02 ` [PATCH RFC 2/5] x86: KVM: svm: avoid flooding logs when skip_emulated_instruction() fails Vitaly Kuznetsov
2019-06-20 18:45 ` Jim Mattson
2019-06-20 11:02 ` [PATCH RFC 3/5] x86: KVM: svm: clear interrupt shadow on all paths in skip_emulated_instruction() Vitaly Kuznetsov
2019-06-20 18:44 ` Jim Mattson
2019-06-21 8:43 ` Vitaly Kuznetsov
2019-07-31 13:50 ` Vitaly Kuznetsov
2019-07-31 16:37 ` Paolo Bonzini
2019-07-31 20:27 ` Jim Mattson
2019-07-31 23:37 ` Sean Christopherson
2019-07-31 23:45 ` Jim Mattson
2019-07-31 23:56 ` Sean Christopherson
2019-08-01 0:13 ` Paolo Bonzini
2019-08-01 0:17 ` Jim Mattson
2019-06-20 11:02 ` [PATCH RFC 4/5] x86: KVM: add xsetbv to the emulator Vitaly Kuznetsov
2019-06-20 12:18 ` Paolo Bonzini
2019-07-31 13:07 ` Vitaly Kuznetsov
2019-07-31 13:14 ` Paolo Bonzini
2019-06-20 11:02 ` [PATCH RFC 5/5] x86: KVM: svm: remove hardcoded instruction length from intercepts Vitaly Kuznetsov
2019-06-20 18:41 ` Jim Mattson
2019-06-20 12:14 ` [PATCH RFC 0/5] x86/KVM/svm: get rid of hardcoded instructions lengths Paolo Bonzini
2019-06-20 12:26 ` Vitaly Kuznetsov
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=20190620110240.25799-1-vkuznets@redhat.com \
--to=vkuznets@redhat.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=rkrcmar@redhat.com \
/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).