[PATCH v4 02/11] KVM: x86/mmu: Move TDP MMU VM init/uninit behind tdp_mmu_enabled

Sean Christopherson
2022-10-12T18:17:41Z

From: David Matlack <dmatlack@google.com>

Move kvm_mmu_{init,uninit}_tdp_mmu() behind tdp_mmu_enabled. This makes
these functions consistent with the rest of the calls into the TDP MMU
from mmu.c, and which is now possible since tdp_mmu_enabled is only
modified when the x86 vendor module is loaded. i.e. It will never change
during the lifetime of a VM.

This change also enabled removing the stub definitions for 32-bit KVM,
as the compiler will just optimize the calls out like it does for all
the other TDP MMU functions.

No functional change intended.

Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/mmu/mmu.c | 11 +++++++----
arch/x86/kvm/mmu/tdp_mmu.c | 6 ------
arch/x86/kvm/mmu/tdp_mmu.h | 7 +++----
3 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 3a370f575808..b2b970e9fa8d 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5984,9 +5984,11 @@ int kvm_mmu_init_vm(struct kvm *kvm)
INIT_LIST_HEAD(&kvm->arch.lpage_disallowed_mmu_pages);
spin_lock_init(&kvm->arch.mmu_unsync_pages_lock);

- r = kvm_mmu_init_tdp_mmu(kvm);
- if (r < 0)
- return r;
+ if (is_tdp_mmu_enabled()) {
+ r = kvm_mmu_init_tdp_mmu(kvm);
+ if (r < 0)
+ return r;
+ }

node->track_write = kvm_mmu_pte_write;
node->track_flush_slot = kvm_mmu_invalidate_zap_pages_in_memslot;
@@ -6016,7 +6018,8 @@ void kvm_mmu_uninit_vm(struct kvm *kvm)

kvm_page_track_unregister_notifier(kvm, node);

- kvm_mmu_uninit_tdp_mmu(kvm);
+ if (is_tdp_mmu_enabled())
+ kvm_mmu_uninit_tdp_mmu(kvm);

mmu_free_vm_memory_caches(kvm);
}
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index cc2a3a511994..f7c4555d5d36 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -15,9 +15,6 @@ int kvm_mmu_init_tdp_mmu(struct kvm *kvm)
{
struct workqueue_struct *wq;

- if (!is_tdp_mmu_enabled())
- return 0;
-
wq = alloc_workqueue("kvm", WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE, 0);
if (!wq)
return -ENOMEM;
@@ -43,9 +40,6 @@ static __always_inline bool kvm_lockdep_assert_mmu_lock_held(struct kvm *kvm,

void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm)
{
- if (!is_tdp_mmu_enabled())
- return;
-
/* Also waits for any queued work items. */
destroy_workqueue(kvm->arch.tdp_mmu_zap_wq);

diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h
index c163f7cc23ca..9d086a103f77 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.h
+++ b/arch/x86/kvm/mmu/tdp_mmu.h
@@ -5,6 +5,9 @@

#include <linux/kvm_host.h>

+int kvm_mmu_init_tdp_mmu(struct kvm *kvm);
+void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm);
+
hpa_t kvm_tdp_mmu_get_vcpu_root_hpa(struct kvm_vcpu *vcpu);

__must_check static inline bool kvm_tdp_mmu_get_root(struct kvm_mmu_page *root)
@@ -66,8 +69,6 @@ u64 *kvm_tdp_mmu_fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, u64 addr,
u64 *spte);

#ifdef CONFIG_X86_64
-int kvm_mmu_init_tdp_mmu(struct kvm *kvm);
-void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm);
static inline bool is_tdp_mmu_page(struct kvm_mmu_page *sp) { return sp->tdp_mmu_page; }

static inline bool is_tdp_mmu(struct kvm_mmu *mmu)
@@ -87,8 +88,6 @@ static inline bool is_tdp_mmu(struct kvm_mmu *mmu)
return sp && is_tdp_mmu_page(sp) && sp->root_count;
}
#else
-static inline int kvm_mmu_init_tdp_mmu(struct kvm *kvm) { return 0; }
-static inline void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm) {}
static inline bool is_tdp_mmu_page(struct kvm_mmu_page *sp) { return false; }
static inline bool is_tdp_mmu(struct kvm_mmu *mmu) { return false; }
#endif