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

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Message-Id: <bd1158dff25ed707e53aca6d7c87d148c4a8f3c6.1637799475.git.isaku.yamahata@intel.com>
Date:   Wed, 24 Nov 2021 16:20:21 -0800
From:   isaku.yamahata@...el.com
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, erdemaktas@...gle.com,
        Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     isaku.yamahata@...el.com, isaku.yamahata@...il.com,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: [RFC PATCH v3 38/59] KVM: x86/mmu: Allow per-VM override of the TDP max page level

From: Sean Christopherson <sean.j.christopherson@...el.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@...el.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.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