linux-kernel - [PATCH v3 08/11] powerpc/kvm/book3s_hv: Applies counting method to monitor lockless pgtbl walks

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Date:   Tue, 24 Sep 2019 18:24:25 -0300
From:   Leonardo Bras <leonardo@...ux.ibm.com>
To:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        kvm-ppc@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-mm@...ck.org
Cc:     Leonardo Bras <leonardo@...ux.ibm.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Arnd Bergmann <arnd@...db.de>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Christophe Leroy <christophe.leroy@....fr>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ganesh Goudar <ganeshgr@...ux.ibm.com>,
        Allison Randal <allison@...utok.net>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        YueHaibing <yuehaibing@...wei.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        John Hubbard <jhubbard@...dia.com>,
        Keith Busch <keith.busch@...el.com>
Subject: [PATCH v3 08/11] powerpc/kvm/book3s_hv: Applies counting method to monitor lockless pgtbl walks

Applies the counting-based method for monitoring all book3s_hv related
functions that do lockless pagetable walks.

Signed-off-by: Leonardo Bras <leonardo@...ux.ibm.com>
---
 arch/powerpc/kvm/book3s_hv_nested.c | 8 ++++++++
 arch/powerpc/kvm/book3s_hv_rm_mmu.c | 9 ++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c
index 735e0ac6f5b2..ed68e57af3a3 100644
--- a/arch/powerpc/kvm/book3s_hv_nested.c
+++ b/arch/powerpc/kvm/book3s_hv_nested.c
@@ -804,6 +804,7 @@ static void kvmhv_update_nest_rmap_rc(struct kvm *kvm, u64 n_rmap,
 		return;
 
 	/* Find the pte */
+	start_lockless_pgtbl_walk(kvm->mm);
 	ptep = __find_linux_pte(gp->shadow_pgtable, gpa, NULL, &shift);
 	/*
 	 * If the pte is present and the pfn is still the same, update the pte.
@@ -815,6 +816,7 @@ static void kvmhv_update_nest_rmap_rc(struct kvm *kvm, u64 n_rmap,
 		__radix_pte_update(ptep, clr, set);
 		kvmppc_radix_tlbie_page(kvm, gpa, shift, lpid);
 	}
+	end_lockless_pgtbl_walk(kvm->mm);
 }
 
 /*
@@ -854,10 +856,12 @@ static void kvmhv_remove_nest_rmap(struct kvm *kvm, u64 n_rmap,
 		return;
 
 	/* Find and invalidate the pte */
+	start_lockless_pgtbl_walk(kvm->mm);
 	ptep = __find_linux_pte(gp->shadow_pgtable, gpa, NULL, &shift);
 	/* Don't spuriously invalidate ptes if the pfn has changed */
 	if (ptep && pte_present(*ptep) && ((pte_val(*ptep) & mask) == hpa))
 		kvmppc_unmap_pte(kvm, ptep, gpa, shift, NULL, gp->shadow_lpid);
+	end_lockless_pgtbl_walk(kvm->mm);
 }
 
 static void kvmhv_remove_nest_rmap_list(struct kvm *kvm, unsigned long *rmapp,
@@ -921,6 +925,7 @@ static bool kvmhv_invalidate_shadow_pte(struct kvm_vcpu *vcpu,
 	int shift;
 
 	spin_lock(&kvm->mmu_lock);
+	start_lockless_pgtbl_walk(kvm->mm);
 	ptep = __find_linux_pte(gp->shadow_pgtable, gpa, NULL, &shift);
 	if (!shift)
 		shift = PAGE_SHIFT;
@@ -928,6 +933,7 @@ static bool kvmhv_invalidate_shadow_pte(struct kvm_vcpu *vcpu,
 		kvmppc_unmap_pte(kvm, ptep, gpa, shift, NULL, gp->shadow_lpid);
 		ret = true;
 	}
+	end_lockless_pgtbl_walk(kvm->mm);
 	spin_unlock(&kvm->mmu_lock);
 
 	if (shift_ret)
@@ -1362,11 +1368,13 @@ static long int __kvmhv_nested_page_fault(struct kvm_run *run,
 	/* See if can find translation in our partition scoped tables for L1 */
 	pte = __pte(0);
 	spin_lock(&kvm->mmu_lock);
+	start_lockless_pgtbl_walk(kvm->mm);
 	pte_p = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
 	if (!shift)
 		shift = PAGE_SHIFT;
 	if (pte_p)
 		pte = *pte_p;
+	end_lockless_pgtbl_walk(kvm->mm);
 	spin_unlock(&kvm->mmu_lock);
 
 	if (!pte_present(pte) || (writing && !(pte_val(pte) & _PAGE_WRITE))) {
diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index 63e0ce91e29d..53ca67492211 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -258,6 +258,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
 	 * If called in real mode we have MSR_EE = 0. Otherwise
 	 * we disable irq above.
 	 */
+	start_lockless_pgtbl_walk(kvm->mm);
 	ptep = __find_linux_pte(pgdir, hva, NULL, &hpage_shift);
 	if (ptep) {
 		pte_t pte;
@@ -311,6 +312,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
 		ptel &= ~(HPTE_R_W|HPTE_R_I|HPTE_R_G);
 		ptel |= HPTE_R_M;
 	}
+	end_lockless_pgtbl_walk(kvm->mm);
 
 	/* Find and lock the HPTEG slot to use */
  do_insert:
@@ -886,10 +888,15 @@ static int kvmppc_get_hpa(struct kvm_vcpu *vcpu, unsigned long gpa,
 	hva = __gfn_to_hva_memslot(memslot, gfn);
 
 	/* Try to find the host pte for that virtual address */
+	start_lockless_pgtbl_walk(kvm->mm);
 	ptep = __find_linux_pte(vcpu->arch.pgdir, hva, NULL, &shift);
-	if (!ptep)
+	if (!ptep) {
+		end_lockless_pgtbl_walk(kvm->mm);
 		return H_TOO_HARD;
+	}
 	pte = kvmppc_read_update_linux_pte(ptep, writing);
+	end_lockless_pgtbl_walk(kvm->mm);
+
 	if (!pte_present(pte))
 		return H_TOO_HARD;
 
-- 
2.20.1