linux-kernel - [PATCH v2 2/3] KVM: x86/mmu: Remove superfluous is_error

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 11 Nov 2019 14:12:28 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Adam Borowski <kilobyte@...band.pl>,
        David Hildenbrand <david@...hat.com>,
        Dan Williams <dan.j.williams@...el.com>
Subject: [PATCH v2 2/3] KVM: x86/mmu: Remove superfluous is_error_pfn() check from THP adjust

Replace the is_error_noslot_pfn() check in transparent_hugepage_adjust()
with an is_noslot_pfn() check.  thp_adjust() cannot be reached with an
error pfn as it is always called after handle_abnormal_pfn(), which
aborts the page fault handler if an error pfn is encountered.  Don't
bother future proofing thp_adjust() with a WARN on is_error_pfn(), as
calling thp_adjust() before handle_abnormal_pfn() is impossible for all
intents and purposes, e.g. thp_adjust() relies on being called after
mmu_notifier_retry() and while holding mmu_lock, thus moving it would
essentially require a complete rewrite of KVM's page fault handlers.

No functional change intended.

Reported-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index bf82b1f2e834..c35c6fb2635a 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3305,7 +3305,7 @@ static void transparent_hugepage_adjust(struct kvm_vcpu *vcpu,
 	 * PT_PAGE_TABLE_LEVEL and there would be no adjustment done
 	 * here.
 	 */
-	if (!is_error_noslot_pfn(pfn) && !kvm_is_reserved_pfn(pfn) &&
+	if (!is_noslot_pfn(pfn) && !kvm_is_reserved_pfn(pfn) &&
 	    !kvm_is_zone_device_pfn(pfn) && level == PT_PAGE_TABLE_LEVEL &&
 	    PageTransCompoundMap(pfn_to_page(pfn)) &&
 	    !mmu_gfn_lpage_is_disallowed(vcpu, gfn, PT_DIRECTORY_LEVEL)) {
-- 
2.24.0