From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Liran Alon <liran.alon@oracle.com>
Cc: "Singh, Brijesh" <brijesh.singh@amd.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"rkrcmar@redhat.com" <rkrcmar@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH 1/2] KVM: SVM: Fix workaround for AMD Errata 1096
Date: Tue, 16 Jul 2019 09:41:51 -0700 [thread overview]
Message-ID: <20190716164151.GC1987@linux.intel.com> (raw)
In-Reply-To: <F2442A5C-702A-433D-9156-056E1844F378@oracle.com>
On Tue, Jul 16, 2019 at 07:20:42PM +0300, Liran Alon wrote:
> How can a SMAP fault occur when CPL==3? One of the conditions for SMAP is
> that CPL<3.
The CPU is effectively at CPL0 when it does the decode assist, e.g.:
1. CPL3 guest hits reserved bit NPT fault (MMIO access)
2. CPU transitions to CPL0 on VM-Exit
3. CPU performs data access on **%rip**, encounters SMAP violation
4. CPU squashes SMAP violation, sets VMCB.insn_len=0
5. CPU delivers VM-Exit to software for original NPT fault
The original NPT fault is due to a reserved bit (or not present) entry for
a MMIO GPA, *not* the GPA corresponding to %rip. The fault on the decode
assist is never delivered to software, it simply results in having invalid
info in the VMCB's insn_bytes and insn_len fields.
next prev parent reply other threads:[~2019-07-16 16:41 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-15 20:30 KVM: SVM: Fix workaround for AMD Errata 1096 Liran Alon
2019-07-15 20:30 ` [PATCH 1/2] " Liran Alon
2019-07-16 15:48 ` Singh, Brijesh
2019-07-16 15:56 ` Liran Alon
2019-07-16 16:07 ` Liran Alon
2019-07-16 16:10 ` Singh, Brijesh
2019-07-16 16:20 ` Liran Alon
2019-07-16 16:41 ` Sean Christopherson [this message]
2019-07-16 16:56 ` Liran Alon
2019-07-16 17:27 ` Sean Christopherson
2019-07-16 17:27 ` Paolo Bonzini
2019-07-16 17:35 ` Liran Alon
2019-07-16 19:28 ` Singh, Brijesh
2019-07-16 19:34 ` Liran Alon
2019-07-16 19:39 ` Paolo Bonzini
2019-07-16 19:45 ` Sean Christopherson
2019-07-16 19:50 ` Liran Alon
2019-07-16 19:47 ` Liran Alon
2019-07-16 19:41 ` Sean Christopherson
2019-07-16 19:52 ` Liran Alon
2019-07-16 20:02 ` Singh, Brijesh
2019-07-16 20:07 ` Sean Christopherson
2019-07-16 20:13 ` Paolo Bonzini
2019-07-16 20:09 ` Liran Alon
2019-07-16 20:27 ` Singh, Brijesh
2019-07-16 20:54 ` Sean Christopherson
2019-07-16 21:53 ` Liran Alon
2019-07-16 18:05 ` Singh, Brijesh
2019-07-16 18:06 ` Singh, Brijesh
2019-07-15 20:30 ` [PATCH 2/2] KVM: x86: Rename need_emulation_on_page_fault() to handle_no_insn_on_page_fault() Liran Alon
2019-07-16 15:48 ` Sean Christopherson
2019-07-16 16:01 ` Liran Alon
2019-07-16 16:10 ` Sean Christopherson
2019-07-16 19:33 ` Singh, Brijesh
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