[PATCH 01/14] KVM: x86/mmu: Enforce max_level on HugeTLB mappings

Sean Christopherson
2020-01-08T20:27:57Z

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@intel.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