From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org, "Kenneth R . Crudup" <kenny@panix.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Xiaoyao Li <xiaoyao.li@intel.com>, Nadav Amit <namit@vmware.com>,
Thomas Hellstrom <thellstrom@vmware.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Tony Luck <tony.luck@intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Jessica Yu <jeyu@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 3/3] KVM: VMX: Extend VMX's #AC interceptor to handle split lock #AC in guest
Date: Thu, 2 Apr 2020 08:55:54 -0700 [thread overview]
Message-ID: <20200402155554.27705-4-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20200402155554.27705-1-sean.j.christopherson@intel.com>
From: Xiaoyao Li <xiaoyao.li@intel.com>
Two types #AC can be generated in Intel CPUs:
1. legacy alignment check #AC
2. split lock #AC
Reflect #AC back into the guest if the guest has legacy alignment checks
enabled or if SLD is disabled. If SLD is enabled, treat the guest like
a host userspace application by calling handle_user_split_lock(). If
the #AC is handled (SLD disabled and TIF_SLD set), then simply resume
the guest. If the #AC isn't handled, i.e. host is sld_fatal, then
forward the #AC to the userspace VMM, similar to sending SIGBUS.
Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/vmx/vmx.c | 30 +++++++++++++++++++++++++++---
1 file changed, 27 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 458e684dfbdc..a96cfda0a5b9 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4623,6 +4623,12 @@ static int handle_machine_check(struct kvm_vcpu *vcpu)
return 1;
}
+static inline bool guest_cpu_alignment_check_enabled(struct kvm_vcpu *vcpu)
+{
+ return vmx_get_cpl(vcpu) == 3 && kvm_read_cr0_bits(vcpu, X86_CR0_AM) &&
+ (kvm_get_rflags(vcpu) & X86_EFLAGS_AC);
+}
+
static int handle_exception_nmi(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -4688,9 +4694,6 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
return handle_rmode_exception(vcpu, ex_no, error_code);
switch (ex_no) {
- case AC_VECTOR:
- kvm_queue_exception_e(vcpu, AC_VECTOR, error_code);
- return 1;
case DB_VECTOR:
dr6 = vmcs_readl(EXIT_QUALIFICATION);
if (!(vcpu->guest_debug &
@@ -4719,6 +4722,27 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
kvm_run->debug.arch.pc = vmcs_readl(GUEST_CS_BASE) + rip;
kvm_run->debug.arch.exception = ex_no;
break;
+ case AC_VECTOR:
+ /*
+ * Reflect #AC to the guest if it's expecting the #AC, i.e. has
+ * legacy alignment check enabled. Pre-check host split lock
+ * turned on to avoid the VMREADs needed to check legacy #AC,
+ * i.e. reflect the #AC if the only possible source is legacy
+ * alignment checks.
+ */
+ if (!boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT) ||
+ guest_cpu_alignment_check_enabled(vcpu)) {
+ kvm_queue_exception_e(vcpu, AC_VECTOR, error_code);
+ return 1;
+ }
+
+ /*
+ * Forward the #AC to userspace if kernel policy does not allow
+ * temporarily disabling split lock detection.
+ */
+ if (handle_user_split_lock(kvm_rip_read(vcpu)))
+ return 1;
+ fallthrough;
default:
kvm_run->exit_reason = KVM_EXIT_EXCEPTION;
kvm_run->ex.exception = ex_no;
--
2.24.1
next prev parent reply other threads:[~2020-04-02 15:56 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-02 12:32 [patch 0/2] x86: Prevent Split-Lock-Detection wreckage on VMX hypervisors Thomas Gleixner
2020-04-02 12:32 ` [patch 1/2] x86,module: Detect VMX modules and disable Split-Lock-Detect Thomas Gleixner
2020-04-02 15:23 ` [patch v2 " Peter Zijlstra
2020-04-02 16:20 ` Xiaoyao Li
2020-04-02 16:25 ` Peter Zijlstra
2020-04-02 16:39 ` Nadav Amit
2020-04-02 16:41 ` Xiaoyao Li
2020-04-02 17:34 ` Thomas Gleixner
2020-04-02 17:51 ` Sean Christopherson
2020-04-02 18:51 ` Peter Zijlstra
2020-04-02 20:23 ` Sean Christopherson
2020-04-02 21:04 ` Thomas Gleixner
2020-04-02 21:16 ` Sean Christopherson
2020-04-03 8:09 ` David Laight
2020-04-03 14:33 ` Peter Zijlstra
2020-04-02 23:42 ` [patch " Rasmus Villemoes
2020-04-03 14:35 ` Jessica Yu
2020-04-03 15:21 ` Peter Zijlstra
2020-04-03 16:01 ` Sean Christopherson
2020-04-03 16:12 ` Peter Zijlstra
2020-04-03 16:16 ` David Laight
2020-04-03 16:39 ` Peter Zijlstra
2020-04-03 16:25 ` Sean Christopherson
2020-04-03 16:40 ` Peter Zijlstra
2020-04-03 16:48 ` Nadav Amit
2020-04-03 17:21 ` Sean Christopherson
2020-04-03 18:53 ` Thomas Gleixner
2020-04-03 20:58 ` Andy Lutomirski
2020-04-03 21:49 ` Thomas Gleixner
2020-04-03 11:29 ` kbuild test robot
2020-04-03 14:43 ` kbuild test robot
2020-04-03 16:36 ` Sean Christopherson
2020-04-03 16:41 ` Peter Zijlstra
2020-04-03 18:35 ` Jessica Yu
2020-04-06 12:23 ` Christoph Hellwig
2020-04-06 14:40 ` Peter Zijlstra
2020-04-06 15:18 ` Christoph Hellwig
2020-04-06 15:22 ` Peter Zijlstra
2020-04-06 18:27 ` Steven Rostedt
2020-04-02 12:33 ` [patch 2/2] x86/kvm/vmx: Prevent split lock detection induced #AC wreckage Thomas Gleixner
2020-04-02 15:30 ` Sean Christopherson
2020-04-02 15:44 ` Nadav Amit
2020-04-02 16:04 ` Sean Christopherson
2020-04-02 16:56 ` Thomas Gleixner
2020-04-02 15:55 ` [PATCH 0/3] x86: KVM: VMX: Add basic split-lock #AC handling Sean Christopherson
2020-04-02 15:55 ` [PATCH 1/3] KVM: x86: Emulate split-lock access as a write in emulator Sean Christopherson
2020-04-02 15:55 ` [PATCH 2/3] x86/split_lock: Refactor and export handle_user_split_lock() for KVM Sean Christopherson
2020-04-02 17:01 ` Thomas Gleixner
2020-04-02 17:19 ` Sean Christopherson
2020-04-02 19:06 ` Thomas Gleixner
2020-04-10 4:39 ` Xiaoyao Li
2020-04-10 10:21 ` Paolo Bonzini
2020-04-02 15:55 ` Sean Christopherson [this message]
2020-04-02 17:19 ` [PATCH 3/3] KVM: VMX: Extend VMX's #AC interceptor to handle split lock #AC in guest Thomas Gleixner
2020-04-02 17:40 ` Sean Christopherson
2020-04-02 20:07 ` Thomas Gleixner
2020-04-02 20:36 ` Andy Lutomirski
2020-04-02 20:48 ` Peter Zijlstra
2020-04-02 20:51 ` Sean Christopherson
2020-04-02 22:27 ` Thomas Gleixner
2020-04-02 22:40 ` Nadav Amit
2020-04-02 23:03 ` Thomas Gleixner
2020-04-02 23:08 ` Steven Rostedt
2020-04-02 23:16 ` Kenneth R. Crudup
2020-04-02 23:18 ` Jim Mattson
2020-04-03 12:16 ` Thomas Gleixner
2020-04-10 10:23 ` [PATCH 0/3] x86: KVM: VMX: Add basic split-lock #AC handling Paolo Bonzini
2020-04-10 11:14 ` Thomas Gleixner
2020-04-02 13:43 ` [patch 0/2] x86: Prevent Split-Lock-Detection wreckage on VMX hypervisors Kenneth R. Crudup
2020-04-02 14:32 ` Peter Zijlstra
2020-04-02 14:41 ` Kenneth R. Crudup
2020-04-02 14:46 ` Peter Zijlstra
2020-04-02 14:53 ` Kenneth R. Crudup
2020-04-02 14:37 ` Thomas Gleixner
2020-04-02 14:47 ` Nadav Amit
2020-04-02 15:11 ` Peter Zijlstra
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