58 lines
2.1 KiB
Diff
58 lines
2.1 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Sean Christopherson <seanjc@google.com>
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Date: Wed, 18 Oct 2023 12:41:03 -0700
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Subject: [PATCH] Revert "nSVM: Check for reserved encodings of TLB_CONTROL in
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nested VMCB"
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Revert KVM's made-up consistency check on SVM's TLB control. The APM says
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that unsupported encodings are reserved, but the APM doesn't state that
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VMRUN checks for a supported encoding. Unless something is called out
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in "Canonicalization and Consistency Checks" or listed as MBZ (Must Be
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Zero), AMD behavior is typically to let software shoot itself in the foot.
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This reverts commit 174a921b6975ef959dd82ee9e8844067a62e3ec1.
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Fixes: 174a921b6975 ("nSVM: Check for reserved encodings of TLB_CONTROL in nested VMCB")
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Reported-by: Stefan Sterz <s.sterz@proxmox.com>
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Closes: https://lkml.kernel.org/r/b9915c9c-4cf6-051a-2d91-44cc6380f455%40proxmox.com
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Cc: stable@vger.kernel.org
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Signed-off-by: Sean Christopherson <seanjc@google.com>
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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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---
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arch/x86/kvm/svm/nested.c | 15 ---------------
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1 file changed, 15 deletions(-)
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diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
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index 36482780a42f..43481f26a34b 100644
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--- a/arch/x86/kvm/svm/nested.c
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+++ b/arch/x86/kvm/svm/nested.c
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@@ -247,18 +247,6 @@ static bool nested_svm_check_bitmap_pa(struct kvm_vcpu *vcpu, u64 pa, u32 size)
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kvm_vcpu_is_legal_gpa(vcpu, addr + size - 1);
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}
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-static bool nested_svm_check_tlb_ctl(struct kvm_vcpu *vcpu, u8 tlb_ctl)
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-{
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- /* Nested FLUSHBYASID is not supported yet. */
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- switch(tlb_ctl) {
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- case TLB_CONTROL_DO_NOTHING:
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- case TLB_CONTROL_FLUSH_ALL_ASID:
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- return true;
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- default:
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- return false;
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- }
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-}
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-
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static bool __nested_vmcb_check_controls(struct kvm_vcpu *vcpu,
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struct vmcb_ctrl_area_cached *control)
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{
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@@ -278,9 +266,6 @@ static bool __nested_vmcb_check_controls(struct kvm_vcpu *vcpu,
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IOPM_SIZE)))
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return false;
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- if (CC(!nested_svm_check_tlb_ctl(vcpu, control->tlb_ctl)))
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- return false;
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-
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if (CC((control->int_ctl & V_NMI_ENABLE_MASK) &&
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!vmcb12_is_intercept(control, INTERCEPT_NMI))) {
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return false;
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