From: Maxim Levitsky <mlevitsk@redhat.com>
To: kvm@vger.kernel.org
Cc: x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
linux-kernel@vger.kernel.org, Joerg Roedel <joro@8bytes.org>,
Thomas Gleixner <tglx@linutronix.de>,
Wanpeng Li <wanpengli@tencent.com>,
"H. Peter Anvin" <hpa@zytor.com>, Borislav Petkov <bp@alien8.de>,
Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Ingo Molnar <mingo@redhat.com>, Jim Mattson <jmattson@google.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Maxim Levitsky <mlevitsk@redhat.com>
Subject: [PATCH] kvm: x86: rewrite kvm_spec_ctrl_valid_bits
Date: Thu, 2 Jul 2020 20:44:55 +0300 [thread overview]
Message-ID: <20200702174455.282252-1-mlevitsk@redhat.com> (raw)
There are few cases when this function was creating a bogus #GP condition,
for example case when and AMD host supports STIBP but doesn't support SSBD.
Follow the rules for AMD and Intel strictly instead.
AMD #GP rules for IA32_SPEC_CTRL can be found here:
https://bugzilla.kernel.org/show_bug.cgi?id=199889
Fixes: 6441fa6178f5 ("KVM: x86: avoid incorrect writes to host MSR_IA32_SPEC_CTRL")
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
arch/x86/kvm/x86.c | 57 ++++++++++++++++++++++++++++++++++------------
1 file changed, 42 insertions(+), 15 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 00c88c2f34e4..a6bed4670b7f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10670,27 +10670,54 @@ bool kvm_arch_no_poll(struct kvm_vcpu *vcpu)
}
EXPORT_SYMBOL_GPL(kvm_arch_no_poll);
-u64 kvm_spec_ctrl_valid_bits(struct kvm_vcpu *vcpu)
+
+static u64 kvm_spec_ctrl_valid_bits_host(void)
+{
+ uint64_t bits = 0;
+
+ if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
+ bits |= SPEC_CTRL_IBRS;
+ if (boot_cpu_has(X86_FEATURE_INTEL_STIBP))
+ bits |= SPEC_CTRL_STIBP;
+ if (boot_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD))
+ bits |= SPEC_CTRL_SSBD;
+
+ if (boot_cpu_has(X86_FEATURE_AMD_IBRS) || boot_cpu_has(X86_FEATURE_AMD_STIBP))
+ bits |= SPEC_CTRL_STIBP | SPEC_CTRL_IBRS;
+
+ if (boot_cpu_has(X86_FEATURE_AMD_SSBD))
+ bits |= SPEC_CTRL_STIBP | SPEC_CTRL_IBRS | SPEC_CTRL_SSBD;
+
+ return bits;
+}
+
+static u64 kvm_spec_ctrl_valid_bits_guest(struct kvm_vcpu *vcpu)
{
- uint64_t bits = SPEC_CTRL_IBRS | SPEC_CTRL_STIBP | SPEC_CTRL_SSBD;
+ uint64_t bits = 0;
- /* The STIBP bit doesn't fault even if it's not advertised */
- if (!guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) &&
- !guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS))
- bits &= ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP);
- if (!boot_cpu_has(X86_FEATURE_SPEC_CTRL) &&
- !boot_cpu_has(X86_FEATURE_AMD_IBRS))
- bits &= ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP);
+ if (guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))
+ bits |= SPEC_CTRL_IBRS;
+ if (guest_cpuid_has(vcpu, X86_FEATURE_INTEL_STIBP))
+ bits |= SPEC_CTRL_STIBP;
+ if (guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL_SSBD))
+ bits |= SPEC_CTRL_SSBD;
- if (!guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL_SSBD) &&
- !guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD))
- bits &= ~SPEC_CTRL_SSBD;
- if (!boot_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) &&
- !boot_cpu_has(X86_FEATURE_AMD_SSBD))
- bits &= ~SPEC_CTRL_SSBD;
+ if (guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS) ||
+ guest_cpuid_has(vcpu, X86_FEATURE_AMD_STIBP))
+ bits |= SPEC_CTRL_STIBP | SPEC_CTRL_IBRS;
+ if (guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD))
+ bits |= SPEC_CTRL_STIBP | SPEC_CTRL_IBRS | SPEC_CTRL_SSBD;
return bits;
}
+
+u64 kvm_spec_ctrl_valid_bits(struct kvm_vcpu *vcpu)
+{
+ return kvm_spec_ctrl_valid_bits_host() &
+ kvm_spec_ctrl_valid_bits_guest(vcpu);
+}
+
+
EXPORT_SYMBOL_GPL(kvm_spec_ctrl_valid_bits);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
--
2.25.4
next reply other threads:[~2020-07-02 17:45 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-02 17:44 Maxim Levitsky [this message]
2020-07-02 18:16 ` [PATCH] kvm: x86: rewrite kvm_spec_ctrl_valid_bits Sean Christopherson
2020-07-05 9:40 ` Maxim Levitsky
2020-07-07 6:11 ` Sean Christopherson
2020-07-07 8:04 ` Paolo Bonzini
2020-07-07 8:14 ` Sean Christopherson
2020-07-07 8:17 ` Paolo Bonzini
2020-07-07 8:26 ` Sean Christopherson
2020-07-07 8:56 ` Wanpeng Li
2020-07-07 11:35 ` Maxim Levitsky
2020-07-07 17:26 ` Paolo Bonzini
2020-07-07 17:27 ` Sean Christopherson
2020-07-07 11:30 ` Maxim Levitsky
2020-07-07 17:26 ` Paolo Bonzini
2020-07-08 11:57 ` [PATCH] kvm: x86: replace kvm_spec_ctrl_test_value with runtime test on the host Maxim Levitsky
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=20200702174455.282252-1-mlevitsk@redhat.com \
--to=mlevitsk@redhat.com \
--cc=bp@alien8.de \
--cc=hpa@zytor.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=pbonzini@redhat.com \
--cc=sean.j.christopherson@intel.com \
--cc=tglx@linutronix.de \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.com \
--cc=x86@kernel.org \
/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).