linux-kernel - [PATCH v3 2/6] KVM: x86/mmu: Move round_gfn_for_level() helper into mmu

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Date:   Fri, 23 Sep 2022 18:52:18 +0800
From:   "Hou Wenlong" <houwenlong.hwl@...group.com>
To:     kvm@...r.kernel.org
Cc:     David Matlack <dmatlack@...gle.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org
Subject: [PATCH v3 2/6] KVM: x86/mmu: Move round_gfn_for_level() helper into mmu_internal.h

Rounding down the GFN to a huge page size is a common pattern
throughout KVM, so move round_gfn_for_level() helper in
tdp_iter.c to mmu_internal.h for common usage. Also rename
it as gfn_round_for_level() to use gfn_* prefix and clean
up the other call site.

Signed-off-by: Hou Wenlong <houwenlong.hwl@...group.com>
---
 arch/x86/kvm/mmu/mmu.c          |  5 +++--
 arch/x86/kvm/mmu/mmu_internal.h |  5 +++++
 arch/x86/kvm/mmu/paging_tmpl.h  |  2 +-
 arch/x86/kvm/mmu/tdp_iter.c     | 11 +++--------
 4 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index ae9f84b0fc64..70c57ed166c7 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3110,7 +3110,7 @@ static int __direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 		if (fault->nx_huge_page_workaround_enabled)
 			disallowed_hugepage_adjust(fault, *it.sptep, it.level);
 
-		base_gfn = fault->gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1);
+		base_gfn = gfn_round_for_level(fault->gfn, it.level);
 		if (it.level == fault->goal_level)
 			break;
 
@@ -4333,7 +4333,8 @@ int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 	if (shadow_memtype_mask && kvm_arch_has_noncoherent_dma(vcpu->kvm)) {
 		for ( ; fault->max_level > PG_LEVEL_4K; --fault->max_level) {
 			int page_num = KVM_PAGES_PER_HPAGE(fault->max_level);
-			gfn_t base = (fault->addr >> PAGE_SHIFT) & ~(page_num - 1);
+			gfn_t base = gfn_round_for_level(fault->addr >> PAGE_SHIFT,
+							 fault->max_level);
 
 			if (kvm_mtrr_check_gfn_range_consistency(vcpu, base, page_num))
 				break;
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index 6651c154f2e0..249bfcd502b4 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -155,6 +155,11 @@ static inline bool kvm_mmu_page_ad_need_write_protect(struct kvm_mmu_page *sp)
 	return kvm_x86_ops.cpu_dirty_log_size && sp->role.guest_mode;
 }
 
+static inline gfn_t gfn_round_for_level(gfn_t gfn, int level)
+{
+	return gfn & -KVM_PAGES_PER_HPAGE(level);
+}
+
 int mmu_try_to_unsync_pages(struct kvm *kvm, const struct kvm_memory_slot *slot,
 			    gfn_t gfn, bool can_unsync, bool prefetch);
 
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 39e0205e7300..4e9f992474cb 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -701,7 +701,7 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault,
 		if (fault->nx_huge_page_workaround_enabled)
 			disallowed_hugepage_adjust(fault, *it.sptep, it.level);
 
-		base_gfn = fault->gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1);
+		base_gfn = gfn_round_for_level(fault->gfn, it.level);
 		if (it.level == fault->goal_level)
 			break;
 
diff --git a/arch/x86/kvm/mmu/tdp_iter.c b/arch/x86/kvm/mmu/tdp_iter.c
index 39b48e7d7d1a..c4bb4abed6d0 100644
--- a/arch/x86/kvm/mmu/tdp_iter.c
+++ b/arch/x86/kvm/mmu/tdp_iter.c
@@ -15,11 +15,6 @@ static void tdp_iter_refresh_sptep(struct tdp_iter *iter)
 	iter->old_spte = kvm_tdp_mmu_read_spte(iter->sptep);
 }
 
-static gfn_t round_gfn_for_level(gfn_t gfn, int level)
-{
-	return gfn & -KVM_PAGES_PER_HPAGE(level);
-}
-
 /*
  * Return the TDP iterator to the root PT and allow it to continue its
  * traversal over the paging structure from there.
@@ -30,7 +25,7 @@ void tdp_iter_restart(struct tdp_iter *iter)
 	iter->yielded_gfn = iter->next_last_level_gfn;
 	iter->level = iter->root_level;
 
-	iter->gfn = round_gfn_for_level(iter->next_last_level_gfn, iter->level);
+	iter->gfn = gfn_round_for_level(iter->next_last_level_gfn, iter->level);
 	tdp_iter_refresh_sptep(iter);
 
 	iter->valid = true;
@@ -97,7 +92,7 @@ static bool try_step_down(struct tdp_iter *iter)
 
 	iter->level--;
 	iter->pt_path[iter->level - 1] = child_pt;
-	iter->gfn = round_gfn_for_level(iter->next_last_level_gfn, iter->level);
+	iter->gfn = gfn_round_for_level(iter->next_last_level_gfn, iter->level);
 	tdp_iter_refresh_sptep(iter);
 
 	return true;
@@ -139,7 +134,7 @@ static bool try_step_up(struct tdp_iter *iter)
 		return false;
 
 	iter->level++;
-	iter->gfn = round_gfn_for_level(iter->gfn, iter->level);
+	iter->gfn = gfn_round_for_level(iter->gfn, iter->level);
 	tdp_iter_refresh_sptep(iter);
 
 	return true;
-- 
2.31.1