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From:   Leonardo Bras <leonardo@linux.ibm.com>
To:     linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        kvm-ppc@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-mm@kvack.org
Cc:     Leonardo Bras <leonardo@linux.ibm.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Arnd Bergmann <arnd@arndb.de>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
        Christophe Leroy <christophe.leroy@c-s.fr>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Nicholas Piggin <npiggin@gmail.com>,
        Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>,
        Allison Randal <allison@lohutok.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ganesh Goudar <ganeshgr@linux.ibm.com>,
        Mike Rapoport <rppt@linux.ibm.com>,
        YueHaibing <yuehaibing@huawei.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Ira Weiny <ira.weiny@intel.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        John Hubbard <jhubbard@nvidia.com>,
        Keith Busch <keith.busch@intel.com>
Subject: [PATCH v4 07/11] powerpc/kvm/e500: Applies counting method to monitor lockless pgtbl walks
Date:   Fri, 27 Sep 2019 20:40:04 -0300
Message-Id: <20190927234008.11513-8-leonardo@linux.ibm.com>
In-Reply-To: <20190927234008.11513-1-leonardo@linux.ibm.com>
References: <20190927234008.11513-1-leonardo@linux.ibm.com>
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Applies the counting-based method for monitoring lockless pgtable walks on
kvmppc_e500_shadow_map().

Fixes the place where local_irq_restore() is called: previously, if ptep
was NULL, local_irq_restore() would never be called.

Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com>
---
 arch/powerpc/kvm/e500_mmu_host.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c
index 321db0fdb9db..a0be76ad8d14 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -473,6 +473,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 	 * We are holding kvm->mmu_lock so a notifier invalidate
 	 * can't run hence pfn won't change.
 	 */
+	start_lockless_pgtbl_walk(kvm->mm);
 	local_irq_save(flags);
 	ptep = find_linux_pte(pgdir, hva, NULL, NULL);
 	if (ptep) {
@@ -481,15 +482,18 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 		if (pte_present(pte)) {
 			wimg = (pte_val(pte) >> PTE_WIMGE_SHIFT) &
 				MAS2_WIMGE_MASK;
-			local_irq_restore(flags);
 		} else {
 			local_irq_restore(flags);
+			end_lockless_pgtbl_walk(kvm->mm);
 			pr_err_ratelimited("%s: pte not present: gfn %lx,pfn %lx\n",
 					   __func__, (long)gfn, pfn);
 			ret = -EINVAL;
 			goto out;
 		}
 	}
+	local_irq_restore(flags);
+	end_lockless_pgtbl_walk(kvm->mm);
+
 	kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg);
 
 	kvmppc_e500_setup_stlbe(&vcpu_e500->vcpu, gtlbe, tsize,
-- 
2.20.1