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[SRU,Bionic,1/2] UBUNTU: SAUCE: Revert "UBUNTU: SAUCE: KVM: nSVM: avoid picking up unsupported bits from L2 in int_ctl"

Message ID 20210816200654.12978-1-cascardo@canonical.com
State New
Headers show
Series LP: #1940134/CVE-2021-3653 - L2 guest on AMD SVM | expand

Commit Message

Thadeu Lima de Souza Cascardo Aug. 16, 2021, 8:06 p.m. UTC 
BugLink: https://bugs.launchpad.net/bugs/1940134

This reverts commit ba798c67f196aa2719a0ca1544d2d7c72b713d05.

When launching L2 Linux guests on systems with VGIF support, they would
fail to boot, not showing any console output.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
---
 arch/x86/include/asm/svm.h | 2 --
 arch/x86/kvm/svm.c         | 8 +-------
 2 files changed, 1 insertion(+), 9 deletions(-)
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Patch

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 2a9e81e93aac..78dd9df88157 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -117,8 +117,6 @@  struct __attribute__ ((__packed__)) vmcb_control_area {
 #define V_IGN_TPR_SHIFT 20
 #define V_IGN_TPR_MASK (1 << V_IGN_TPR_SHIFT)
 
-#define V_IRQ_INJECTION_BITS_MASK (V_IRQ_MASK | V_INTR_PRIO_MASK | V_IGN_TPR_MASK)
-
 #define V_INTR_MASKING_SHIFT 24
 #define V_INTR_MASKING_MASK (1 << V_INTR_MASKING_SHIFT)
 
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index abb93d4b9f06..db07c4131318 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3134,13 +3134,7 @@  static void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
 	svm->nested.intercept            = nested_vmcb->control.intercept;
 
 	svm_flush_tlb(&svm->vcpu, true);
-
-	svm->vmcb->control.int_ctl &=
-			V_INTR_MASKING_MASK | V_GIF_ENABLE_MASK | V_GIF_MASK;
-
-	svm->vmcb->control.int_ctl |= nested_vmcb->control.int_ctl &
-			(V_TPR_MASK | V_IRQ_INJECTION_BITS_MASK);
-
+	svm->vmcb->control.int_ctl = nested_vmcb->control.int_ctl | V_INTR_MASKING_MASK;
 	if (nested_vmcb->control.int_ctl & V_INTR_MASKING_MASK)
 		svm->vcpu.arch.hflags |= HF_VINTR_MASK;
 	else