[RFC PATCH v3 38/59] KVM: x86/mmu: Allow per-VM override of the TDP max page level

isaku.yamahata
2021-11-25T00:21:50Z

From: Sean Christopherson <sean.j.christopherson@intel.com>

TODO: This is tentative patch. Support large page and delete this patch.

Allow TDX to effectively disable large pages, as SEPT will initially
support only 4k pages.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/mmu.h | 2 +-
arch/x86/kvm/mmu/mmu.c | 2 ++
3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 7ce0641d54dd..a2027bc14e41 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1054,6 +1054,7 @@ struct kvm_arch {
unsigned long n_requested_mmu_pages;
unsigned long n_max_mmu_pages;
unsigned int indirect_shadow_pages;
+ int tdp_max_page_level;
u8 mmu_valid_gen;
struct hlist_head mmu_page_hash[KVM_NUM_MMU_PAGES];
struct list_head active_mmu_pages;
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 168dcd4e0102..2c4b8fde66d9 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -191,7 +191,7 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
.is_tdp = likely(vcpu->arch.mmu->page_fault == kvm_tdp_page_fault),
.nx_huge_page_workaround_enabled = is_nx_huge_page_enabled(),

- .max_level = KVM_MAX_HUGEPAGE_LEVEL,
+ .max_level = vcpu->kvm->arch.tdp_max_page_level,
.req_level = PG_LEVEL_4K,
.goal_level = PG_LEVEL_4K,
};
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 63d2e3e85c08..7d3830508a44 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -6102,6 +6102,8 @@ void kvm_mmu_init_vm(struct kvm *kvm)
node->track_write = kvm_mmu_pte_write;
node->track_flush_slot = kvm_mmu_invalidate_zap_pages_in_memslot;
kvm_page_track_register_notifier(kvm, node);
+
+ kvm->arch.tdp_max_page_level = KVM_MAX_HUGEPAGE_LEVEL;
}

void kvm_mmu_uninit_vm(struct kvm *kvm)
--
2.25.1