Commit 2ac48130 authored by Sean Christopherson's avatar Sean Christopherson Committed by Ma Wupeng
Browse files

Revert "nSVM: Check for reserved encodings of TLB_CONTROL in nested VMCB" 

stable inclusion
from stable-v6.6.14
commit 0dfcefc97300eceebc1783fb636955223118bc49
bugzilla: https://gitee.com/openeuler/kernel/issues/I99TJK

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0dfcefc97300eceebc1783fb636955223118bc49



--------------------------------

commit a484755ab2526ebdbe042397cdd6e427eb4b1a68 upstream.

Revert KVM's made-up consistency check on SVM's TLB control.  The APM says
that unsupported encodings are reserved, but the APM doesn't state that
VMRUN checks for a supported encoding.  Unless something is called out
in "Canonicalization and Consistency Checks" or listed as MBZ (Must Be
Zero), AMD behavior is typically to let software shoot itself in the foot.

This reverts commit 174a921b.

Fixes: 174a921b ("nSVM: Check for reserved encodings of TLB_CONTROL in nested VMCB")
Reported-by: default avatarStefan Sterz <s.sterz@proxmox.com>
Closes: https://lkml.kernel.org/r/b9915c9c-4cf6-051a-2d91-44cc6380f455%40proxmox.com


Cc: stable@vger.kernel.org
Reviewed-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20231018194104.1896415-2-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarZhangPeng <zhangpeng362@huawei.com>
parent a8dfa243

arch/x86/kvm/svm/nested.c

+0 −15
Original line number Diff line number Diff line
@@ -247,18 +247,6 @@ static bool nested_svm_check_bitmap_pa(struct kvm_vcpu *vcpu, u64 pa, u32 size) 
	    kvm_vcpu_is_legal_gpa(vcpu, addr + size - 1);

}



static bool nested_svm_check_tlb_ctl(struct kvm_vcpu *vcpu, u8 tlb_ctl)

{

	/* Nested FLUSHBYASID is not supported yet.  */

	switch(tlb_ctl) {

		case TLB_CONTROL_DO_NOTHING:

		case TLB_CONTROL_FLUSH_ALL_ASID:

			return true;

		default:

			return false;

	}

}



static bool __nested_vmcb_check_controls(struct kvm_vcpu *vcpu,

					 struct vmcb_ctrl_area_cached *control)

{
@@ -278,9 +266,6 @@ static bool __nested_vmcb_check_controls(struct kvm_vcpu *vcpu, 
					   IOPM_SIZE)))

		return false;



	if (CC(!nested_svm_check_tlb_ctl(vcpu, control->tlb_ctl)))

		return false;



	if (CC((control->int_ctl & V_NMI_ENABLE_MASK) &&

	       !vmcb12_is_intercept(control, INTERCEPT_NMI))) {

		return false;