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: "Song Liu" <songliubraving@fb.com>,
"Michal Hocko" <mhocko@suse.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
"Dmitry V. Levin" <ldv@altlinux.org>,
"Keith Busch" <keith.busch@intel.com>,
"Paul Mackerras" <paulus@samba.org>,
"Christoph Lameter" <cl@linux.com>,
"Ira Weiny" <ira.weiny@intel.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Elena Reshetova" <elena.reshetova@intel.com>,
"Andrea Arcangeli" <aarcange@redhat.com>,
"Santosh Sivaraj" <santosh@fossix.org>,
"Davidlohr Bueso" <dave@stgolabs.net>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
"Bartlomiej Zolnierkiewicz" <b.zolnierkie@samsung.com>,
"Mike Rapoport" <rppt@linux.ibm.com>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"Allison Randal" <allison@lohutok.net>,
"Mahesh Salgaonkar" <mahesh@linux.vnet.ibm.com>,
"Leonardo Bras" <leonardo@linux.ibm.com>,
"Alexey Dobriyan" <adobriyan@gmail.com>,
"Ingo Molnar" <mingo@kernel.org>,
"Ralph Campbell" <rcampbell@nvidia.com>,
"Arnd Bergmann" <arnd@arndb.de>, "Jann Horn" <jannh@google.com>,
"John Hubbard" <jhubbard@nvidia.com>,
"Jesper Dangaard Brouer" <brouer@redhat.com>,
"Nicholas Piggin" <npiggin@gmail.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Andrey Ryabinin" <aryabinin@virtuozzo.com>,
"Dan Williams" <dan.j.williams@intel.com>,
"Reza Arbab" <arbab@linux.ibm.com>,
"Vlastimil Babka" <vbabka@suse.cz>,
"Christian Brauner" <christian.brauner@ubuntu.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Souptick Joarder" <jrdr.linux@gmail.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Logan Gunthorpe" <logang@deltatee.com>,
"Roman Gushchin" <guro@fb.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: [PATCH v5 08/11] powerpc/kvm/book3s_hv: Applies counting method to monitor lockless pgtbl walks
Date: Wed, 2 Oct 2019 22:33:22 -0300 [thread overview]
Message-ID: <20191003013325.2614-9-leonardo@linux.ibm.com> (raw)
In-Reply-To: <20191003013325.2614-1-leonardo@linux.ibm.com>
Applies the counting-based method for monitoring all book3s_hv related
functions that do lockless pagetable walks.
Adds comments explaining that some lockless pagetable walks don't need
protection due to guest pgd not being a target of THP collapse/split, or
due to being called from Realmode + MSR_EE = 0
kvmppc_do_h_enter: Fixes where local_irq_restore() must be placed (after
the last usage of ptep).
Given that some of these functions can be called in real mode, and others
always are, we use __{begin,end}_lockless_pgtbl_walk so we can decide when
to disable interrupts.
Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com>
---
arch/powerpc/kvm/book3s_hv_nested.c | 22 ++++++++++++++++++--
arch/powerpc/kvm/book3s_hv_rm_mmu.c | 32 ++++++++++++++++-------------
2 files changed, 38 insertions(+), 16 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c
index cdf30c6eaf54..89944c699fd6 100644
--- a/arch/powerpc/kvm/book3s_hv_nested.c
+++ b/arch/powerpc/kvm/book3s_hv_nested.c
@@ -803,7 +803,11 @@ static void kvmhv_update_nest_rmap_rc(struct kvm *kvm, u64 n_rmap,
if (!gp)
return;
- /* Find the pte */
+ /* Find the pte:
+ * We are walking the nested guest (partition-scoped) page table here.
+ * We can do this without disabling irq because the Linux MM
+ * subsystem doesn't do THP splits and collapses on this tree.
+ */
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.
@@ -853,7 +857,11 @@ static void kvmhv_remove_nest_rmap(struct kvm *kvm, u64 n_rmap,
if (!gp)
return;
- /* Find and invalidate the pte */
+ /* Find and invalidate the pte:
+ * We are walking the nested guest (partition-scoped) page table here.
+ * We can do this without disabling irq because the Linux MM
+ * subsystem doesn't do THP splits and collapses on this tree.
+ */
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))
@@ -921,6 +929,11 @@ static bool kvmhv_invalidate_shadow_pte(struct kvm_vcpu *vcpu,
int shift;
spin_lock(&kvm->mmu_lock);
+ /*
+ * We are walking the nested guest (partition-scoped) page table here.
+ * We can do this without disabling irq because the Linux MM
+ * subsystem doesn't do THP splits and collapses on this tree.
+ */
ptep = __find_linux_pte(gp->shadow_pgtable, gpa, NULL, &shift);
if (!shift)
shift = PAGE_SHIFT;
@@ -1362,6 +1375,11 @@ 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);
+ /*
+ * We are walking the secondary (partition-scoped) page table here.
+ * We can do this without disabling irq because the Linux MM
+ * subsystem doesn't do THP splits and collapses on this tree.
+ */
pte_p = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
if (!shift)
shift = PAGE_SHIFT;
diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index 220305454c23..a8be42f5be1e 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -210,7 +210,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
pte_t *ptep;
unsigned int writing;
unsigned long mmu_seq;
- unsigned long rcbits, irq_flags = 0;
+ unsigned long rcbits, irq_mask = 0;
if (kvm_is_radix(kvm))
return H_FUNCTION;
@@ -252,12 +252,8 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
* If we had a page table table change after lookup, we would
* retry via mmu_notifier_retry.
*/
- if (!realmode)
- local_irq_save(irq_flags);
- /*
- * If called in real mode we have MSR_EE = 0. Otherwise
- * we disable irq above.
- */
+ irq_mask = __begin_lockless_pgtbl_walk(kvm->mm, !realmode);
+
ptep = __find_linux_pte(pgdir, hva, NULL, &hpage_shift);
if (ptep) {
pte_t pte;
@@ -272,8 +268,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
* to <= host page size, if host is using hugepage
*/
if (host_pte_size < psize) {
- if (!realmode)
- local_irq_restore(flags);
+ __end_lockless_pgtbl_walk(kvm->mm, irq_mask, !realmode);
return H_PARAMETER;
}
pte = kvmppc_read_update_linux_pte(ptep, writing);
@@ -287,8 +282,6 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
pa |= gpa & ~PAGE_MASK;
}
}
- if (!realmode)
- local_irq_restore(irq_flags);
ptel &= HPTE_R_KEY | HPTE_R_PP0 | (psize-1);
ptel |= pa;
@@ -302,8 +295,10 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
/*If we had host pte mapping then Check WIMG */
if (ptep && !hpte_cache_flags_ok(ptel, is_ci)) {
- if (is_ci)
+ if (is_ci) {
+ __end_lockless_pgtbl_walk(kvm->mm, irq_mask, !realmode);
return H_PARAMETER;
+ }
/*
* Allow guest to map emulated device memory as
* uncacheable, but actually make it cacheable.
@@ -311,6 +306,7 @@ 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, irq_mask, !realmode);
/* Find and lock the HPTEG slot to use */
do_insert:
@@ -907,11 +903,19 @@ static int kvmppc_get_hpa(struct kvm_vcpu *vcpu, unsigned long gpa,
/* Translate to host virtual address */
hva = __gfn_to_hva_memslot(memslot, gfn);
- /* Try to find the host pte for that virtual address */
+ /* Try to find the host pte for that virtual address :
+ * Called by hcall_real_table (real mode + MSR_EE=0)
+ * Interrupts are disabled here.
+ */
+ __begin_lockless_pgtbl_walk(kvm->mm, false);
ptep = __find_linux_pte(vcpu->arch.pgdir, hva, NULL, &shift);
- if (!ptep)
+ if (!ptep) {
+ __end_lockless_pgtbl_walk(kvm->mm, 0, false);
return H_TOO_HARD;
+ }
pte = kvmppc_read_update_linux_pte(ptep, writing);
+ __end_lockless_pgtbl_walk(kvm->mm, 0, false);
+
if (!pte_present(pte))
return H_TOO_HARD;
--
2.20.1
next prev parent reply other threads:[~2019-10-03 1:52 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-03 1:33 [PATCH v5 00/11] Introduces new count-based method for tracking lockless pagetable walks Leonardo Bras
2019-10-03 1:33 ` [PATCH v5 01/11] asm-generic/pgtable: Adds generic functions to monitor lockless pgtable walks Leonardo Bras
2019-10-03 7:11 ` Peter Zijlstra
2019-10-03 11:51 ` Peter Zijlstra
2019-10-03 20:40 ` John Hubbard
2019-10-04 11:24 ` Peter Zijlstra
2019-10-03 21:24 ` Leonardo Bras
2019-10-04 11:28 ` Peter Zijlstra
2019-10-09 18:09 ` Leonardo Bras
2019-10-05 8:35 ` Aneesh Kumar K.V
2019-10-08 14:47 ` Kirill A. Shutemov
2019-10-03 1:33 ` [PATCH v5 02/11] powerpc/mm: Adds counting method " Leonardo Bras
2019-10-08 15:11 ` Christopher Lameter
2019-10-08 17:13 ` Leonardo Bras
2019-10-08 17:43 ` Christopher Lameter
2019-10-08 18:02 ` Leonardo Bras
2019-10-08 18:27 ` Christopher Lameter
2019-10-03 1:33 ` [PATCH v5 03/11] mm/gup: Applies counting method to monitor gup_pgd_range Leonardo Bras
2019-10-03 1:33 ` [PATCH v5 04/11] powerpc/mce_power: Applies counting method to monitor lockless pgtbl walks Leonardo Bras
2019-10-03 1:33 ` [PATCH v5 05/11] powerpc/perf: " Leonardo Bras
2019-10-03 1:33 ` [PATCH v5 06/11] powerpc/mm/book3s64/hash: " Leonardo Bras
2019-10-03 1:33 ` [PATCH v5 07/11] powerpc/kvm/e500: " Leonardo Bras
2019-10-03 1:33 ` Leonardo Bras [this message]
2019-10-03 1:33 ` [PATCH v5 09/11] powerpc/kvm/book3s_64: " Leonardo Bras
2019-10-03 1:33 ` [PATCH v5 10/11] mm/Kconfig: Adds config option to track lockless pagetable walks Leonardo Bras
2019-10-03 2:08 ` Qian Cai
2019-10-03 19:04 ` Leonardo Bras
2019-10-03 19:08 ` Leonardo Bras
2019-10-03 7:44 ` Peter Zijlstra
2019-10-03 20:40 ` Leonardo Bras
2019-10-03 1:33 ` [PATCH v5 11/11] powerpc/mm/book3s64/pgtable: Uses counting method to skip serializing Leonardo Bras
2019-10-03 7:29 ` [PATCH v5 00/11] Introduces new count-based method for tracking lockless pagetable walks Peter Zijlstra
2019-10-03 20:36 ` Leonardo Bras
2019-10-03 20:49 ` John Hubbard
2019-10-03 21:38 ` Leonardo Bras
2019-10-04 11:42 ` Peter Zijlstra
2019-10-04 12:57 ` Peter Zijlstra
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