linux-kernel - [PATCH 01/14] KVM: x86/mmu: Enforce max

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Date:   Wed,  8 Jan 2020 12:24:35 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Paul Mackerras <paulus@...abs.org>,
        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>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        kvm-ppc@...r.kernel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        syzbot+c9d1fb51ac9d0d10c39d@...kaller.appspotmail.com,
        Andrea Arcangeli <aarcange@...hat.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Barret Rhoden <brho@...gle.com>,
        David Hildenbrand <david@...hat.com>,
        Jason Zeng <jason.zeng@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Liran Alon <liran.alon@...cle.com>,
        linux-nvdimm <linux-nvdimm@...ts.01.org>
Subject: [PATCH 01/14] KVM: x86/mmu: Enforce max_level on HugeTLB mappings

Limit KVM's mapping level for HugeTLB based on its calculated max_level.
The max_level check prior to invoking host_mapping_level() only filters
out the case where KVM cannot create a 2mb mapping, it doesn't handle
the scenario where KVM can create a 2mb but not 1gb mapping, and the
host is using a 1gb HugeTLB mapping.

Fixes: ad163aa8903d ("KVM: x86/mmu: Persist gfn_lpage_is_disallowed() to max_level")
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/mmu/mmu.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 7269130ea5e2..8e822c09170d 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1330,7 +1330,7 @@ gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn,
 static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn,
 			 int *max_levelp)
 {
-	int max_level = *max_levelp;
+	int host_level, max_level = *max_levelp;
 	struct kvm_memory_slot *slot;
 
 	if (unlikely(max_level == PT_PAGE_TABLE_LEVEL))
@@ -1362,7 +1362,8 @@ static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn,
 	 * So, do not propagate host_mapping_level() to max_level as KVM can
 	 * still promote the guest mapping to a huge page in the THP case.
 	 */
-	return host_mapping_level(vcpu->kvm, large_gfn);
+	host_level = host_mapping_level(vcpu->kvm, large_gfn);
+	return min(host_level, max_level);
 }
 
 /*
-- 
2.24.1