Patch "KVM: x86: Handle 32-bit wrap of EIP for EMULTYPE_SKIP with flat code seg" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    KVM: x86: Handle 32-bit wrap of EIP for EMULTYPE_SKIP with flat code seg

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-x86-handle-32-bit-wrap-of-eip-for-emultype_skip-.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit ebdb52f41732c62c9316577c2fe2f010650cb804
Author: Sean Christopherson <seanjc@xxxxxxxxxx>
Date:   Tue Nov 2 17:15:29 2021 +0800

    KVM: x86: Handle 32-bit wrap of EIP for EMULTYPE_SKIP with flat code seg
    
    [ Upstream commit 5e854864ee4384736f27a986633bae21731a4e4e ]
    
    Truncate the new EIP to a 32-bit value when handling EMULTYPE_SKIP as the
    decode phase does not truncate _eip.  Wrapping the 32-bit boundary is
    legal if and only if CS is a flat code segment, but that check is
    implicitly handled in the form of limit checks in the decode phase.
    
    Opportunstically prepare for a future fix by storing the result of any
    truncation in "eip" instead of "_eip".
    
    Fixes: 1957aa63be53 ("KVM: VMX: Handle single-step #DB for EMULTYPE_SKIP on EPT misconfig")
    Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
    Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
    Message-Id: <093eabb1eab2965201c9b018373baf26ff256d85.1635842679.git.houwenlong93@xxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 33457b27e220b..6b76486702ded 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7999,7 +7999,12 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 	 * updating interruptibility state and injecting single-step #DBs.
 	 */
 	if (emulation_type & EMULTYPE_SKIP) {
-		kvm_rip_write(vcpu, ctxt->_eip);
+		if (ctxt->mode != X86EMUL_MODE_PROT64)
+			ctxt->eip = (u32)ctxt->_eip;
+		else
+			ctxt->eip = ctxt->_eip;
+
+		kvm_rip_write(vcpu, ctxt->eip);
 		if (ctxt->eflags & X86_EFLAGS_RF)
 			kvm_set_rflags(vcpu, ctxt->eflags & ~X86_EFLAGS_RF);
 		return 1;