From: Paolo Bonzini <pbonzini@redhat.com>
To: Marios Pomonis <pomonis@google.com>,
rkrcmar@redhat.com,
Sean Christopherson <sean.j.christopherson@intel.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, Nick Finco <nifi@google.com>,
Andrew Honig <ahonig@google.com>,
stable@vger.kernel.org
Subject: Re: [PATCH v2 10/13] KVM: x86: Protect memory accesses from Spectre-v1/L1TF attacks in x86.c
Date: Sat, 18 Jan 2020 21:13:53 +0100 [thread overview]
Message-ID: <d8f47c12-3301-cb70-8d08-fe93450d19eb@redhat.com> (raw)
In-Reply-To: <20191211204753.242298-11-pomonis@google.com>
On 11/12/19 21:47, Marios Pomonis wrote:
> This fixes Spectre-v1/L1TF vulnerabilities in
> vmx_read_guest_seg_selector(), vmx_read_guest_seg_base(),
> vmx_read_guest_seg_limit() and vmx_read_guest_seg_ar().
> These functions contain index computations based on the
> (attacker-influenced) segment value.
>
> Fixes: commit 2fb92db1ec08 ("KVM: VMX: Cache vmcs segment fields")
I think we could instead do
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 2d4faefe8dd4..20c0cbdff1be 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -5195,16 +5195,28 @@ int x86_decode_insn(struct x86_emulate_ctxt
*ctxt, void *insn, int insn_len)
ctxt->ad_bytes = def_ad_bytes ^ 6;
break;
case 0x26: /* ES override */
+ has_seg_override = true;
+ ctxt->seg_override = VCPU_SREG_ES;
+ break;
case 0x2e: /* CS override */
+ has_seg_override = true;
+ ctxt->seg_override = VCPU_SREG_CS;
+ break;
case 0x36: /* SS override */
+ has_seg_override = true;
+ ctxt->seg_override = VCPU_SREG_SS;
+ break;
case 0x3e: /* DS override */
has_seg_override = true;
- ctxt->seg_override = (ctxt->b >> 3) & 3;
+ ctxt->seg_override = VCPU_SREG_DS;
break;
case 0x64: /* FS override */
+ has_seg_override = true;
+ ctxt->seg_override = VCPU_SREG_FS;
+ break;
case 0x65: /* GS override */
has_seg_override = true;
- ctxt->seg_override = ctxt->b & 7;
+ ctxt->seg_override = VCPU_SREG_GS;
break;
case 0x40 ... 0x4f: /* REX */
if (mode != X86EMUL_MODE_PROT64)
so that the segment is never calculated.
Paolo
next prev parent reply other threads:[~2020-01-18 20:13 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-11 20:47 [PATCH v2 00/13] KVM: x86: Extend Spectre-v1 mitigation Marios Pomonis
2019-12-11 20:47 ` [PATCH v2 01/13] KVM: x86: Protect x86_decode_insn from Spectre-v1/L1TF attacks Marios Pomonis
2020-01-06 20:16 ` Jim Mattson
2019-12-11 20:47 ` [PATCH v2 02/13] KVM: x86: Protect kvm_hv_msr_[get|set]_crash_data() " Marios Pomonis
2019-12-12 9:43 ` Vitaly Kuznetsov
2019-12-12 17:11 ` Marios Pomonis
2019-12-12 17:31 ` Christian Borntraeger
2019-12-12 17:44 ` Jim Mattson
2019-12-12 17:47 ` Christian Borntraeger
2020-01-06 20:16 ` Jim Mattson
2019-12-11 20:47 ` [PATCH v2 03/13] KVM: x86: Refactor picdev_write() to prevent " Marios Pomonis
2020-01-06 20:17 ` Jim Mattson
2019-12-11 20:47 ` [PATCH v2 04/13] KVM: x86: Protect ioapic_read_indirect() from " Marios Pomonis
2020-01-06 20:17 ` Jim Mattson
2019-12-11 20:47 ` [PATCH v2 05/13] KVM: x86: Protect ioapic_write_indirect() " Marios Pomonis
2020-01-06 20:17 ` Jim Mattson
2019-12-11 20:47 ` [PATCH v2 06/13] KVM: x86: Protect kvm_lapic_reg_write() " Marios Pomonis
2020-01-06 20:17 ` Jim Mattson
2019-12-11 20:47 ` [PATCH v2 07/13] KVM: x86: Protect MSR-based index computations in fixed_msr_to_seg_unit() " Marios Pomonis
[not found] ` <20191225235523.470232075B@mail.kernel.org>
2019-12-30 23:14 ` Marios Pomonis
2020-01-06 20:18 ` Jim Mattson
2019-12-11 20:47 ` [PATCH v2 08/13] KVM: x86: Protect MSR-based index computations in pmu.h " Marios Pomonis
2020-01-06 20:18 ` Jim Mattson
2019-12-11 20:47 ` [PATCH v2 09/13] KVM: x86: Protect MSR-based index computations from Spectre-v1/L1TF attacks in x86.c Marios Pomonis
2020-01-06 20:18 ` Jim Mattson
2019-12-11 20:47 ` [PATCH v2 10/13] KVM: x86: Protect memory accesses " Marios Pomonis
2020-01-06 20:19 ` Jim Mattson
2020-01-18 20:13 ` Paolo Bonzini [this message]
2019-12-11 20:47 ` [PATCH v2 11/13] KVM: x86: Protect exit_reason from being used in Spectre-v1/L1TF attacks Marios Pomonis
2019-12-11 20:47 ` [PATCH v2 12/13] KVM: x86: Protect DR-based index computations from " Marios Pomonis
2020-01-06 20:19 ` Jim Mattson
2019-12-11 20:47 ` [PATCH v2 13/13] KVM: x86: Protect pmu_intel.c " Marios Pomonis
2020-01-06 20:19 ` Jim Mattson
2020-01-18 20:18 ` [PATCH v2 00/13] KVM: x86: Extend Spectre-v1 mitigation Paolo Bonzini
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