linux-kernel - [PATCH 22/22] ***HACK*** KVM: x86: Don't take mmu

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Message-ID: <20240809194335.1726916-23-seanjc@google.com>
Date: Fri,  9 Aug 2024 12:43:34 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Oliver Upton <oliver.upton@...ux.dev>, Marc Zyngier <maz@...nel.org>, Peter Xu <peterx@...hat.com>, 
	James Houghton <jthoughton@...gle.com>
Subject: [PATCH 22/22] ***HACK*** KVM: x86: Don't take mmu_lock when aging gfns

DO NOT MERGE, this is a horrific hack, breaks TDP MMU, etc.

Not-signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/svm.c | 2 ++
 arch/x86/kvm/vmx/vmx.c | 2 ++
 virt/kvm/kvm_main.c    | 7 ++++---
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index c115d26844f7..e5c5d0f9a69d 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -5300,6 +5300,8 @@ static __init int svm_hardware_setup(void)
 	if (!boot_cpu_has(X86_FEATURE_NPT))
 		npt_enabled = false;
 
+	npt_enabled = false;
+
 	/* Force VM NPT level equal to the host's paging level */
 	kvm_configure_mmu(npt_enabled, get_npt_level(),
 			  get_npt_level(), PG_LEVEL_1G);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index f18c2d8c7476..28f3493d6391 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8419,6 +8419,8 @@ __init int vmx_hardware_setup(void)
 	    !cpu_has_vmx_invept_global())
 		enable_ept = 0;
 
+	enable_ept = 0;
+
 	/* NX support is required for shadow paging. */
 	if (!enable_ept && !boot_cpu_has(X86_FEATURE_NX)) {
 		pr_err_ratelimited("NX (Execute Disable) not supported\n");
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d0788d0a72cc..1b9b5dea2ac8 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -642,10 +642,11 @@ static __always_inline kvm_mn_ret_t __kvm_handle_hva_range(struct kvm *kvm,
 			gfn_range.slot = slot;
 
 			if (!r.found_memslot) {
-				r.found_memslot = true;
-				KVM_MMU_LOCK(kvm);
-				if (!IS_KVM_NULL_FN(range->on_lock))
+				if (!IS_KVM_NULL_FN(range->on_lock)) {
+					r.found_memslot = true;
+					KVM_MMU_LOCK(kvm);
 					range->on_lock(kvm);
+				}
 
 				if (IS_KVM_NULL_FN(range->handler))
 					goto mmu_unlock;
-- 
2.46.0.76.ge559c4bf1a-goog