From: Leonardo Bras <leonardo@linux.ibm.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Arnd Bergmann <arnd@arndb.de>,
Andrew Morton <akpm@linux-foundation.org>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
Nicholas Piggin <npiggin@gmail.com>,
Christophe Leroy <christophe.leroy@c-s.fr>,
Steven Price <steven.price@arm.com>,
Robin Murphy <robin.murphy@arm.com>,
Leonardo Bras <leonardo@linux.ibm.com>,
Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>,
Balbir Singh <bsingharora@gmail.com>,
Reza Arbab <arbab@linux.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Allison Randal <allison@lohutok.net>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Mike Rapoport <rppt@linux.ibm.com>,
Michal Suchanek <msuchanek@suse.de>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
kvm-ppc@vger.kernel.org, linux-arch@vger.kernel.org,
linux-mm@kvack.org
Subject: [PATCH v6 09/11] powerpc/kvm/book3s_64: Use functions to track lockless pgtbl walks
Date: Thu, 6 Feb 2020 00:08:58 -0300 [thread overview]
Message-ID: <20200206030900.147032-10-leonardo@linux.ibm.com> (raw)
Message-ID: <20200206030858.jwNHx-_DQNwpvo9qCSvx8dA4WPsheyCPeUvB-98BloU@z> (raw)
In-Reply-To: <20200206030900.147032-1-leonardo@linux.ibm.com>
Applies the new tracking functions to all book3s_64 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.
Given that some of these functions always are called in realmode, we use
__{begin,end}_lockless_pgtbl_walk so we can decide when to disable
interrupts.
local_irq_{save,restore} is already inside {begin,end}_lockless_pgtbl_walk,
so there is no need to repeat it here.
Variable that saves the irq mask was renamed from flags to irq_mask so it
doesn't lose meaning now it's not directly passed to local_irq_* functions.
There are also a function that uses local_irq_{en,dis}able, so the return
value of begin_lockless_pgtbl_walk() is ignored and we pass IRQS_ENABLED to
end_lockless_pgtbl_walk() to mimic the effect of local_irq_enable().
Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com>
---
arch/powerpc/kvm/book3s_64_mmu_hv.c | 6 ++---
arch/powerpc/kvm/book3s_64_mmu_radix.c | 34 +++++++++++++++++++++++---
arch/powerpc/kvm/book3s_64_vio_hv.c | 6 ++++-
3 files changed, 39 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 6c372f5c61b6..e7ce29a5df60 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -605,19 +605,19 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
/* if the guest wants write access, see if that is OK */
if (!writing && hpte_is_writable(r)) {
pte_t *ptep, pte;
- unsigned long flags;
+ unsigned long irq_mask;
/*
* We need to protect against page table destruction
* hugepage split and collapse.
*/
- local_irq_save(flags);
+ irq_mask = begin_lockless_pgtbl_walk();
ptep = find_current_mm_pte(mm->pgd, hva, NULL, NULL);
if (ptep) {
pte = kvmppc_read_update_linux_pte(ptep, 1);
if (__pte_write(pte))
write_ok = 1;
}
- local_irq_restore(flags);
+ end_lockless_pgtbl_walk(irq_mask);
}
}
diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
index 803940d79b73..cda2e455baf2 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
@@ -813,20 +813,20 @@ int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcpu,
* Read the PTE from the process' radix tree and use that
* so we get the shift and attribute bits.
*/
- local_irq_disable();
+ begin_lockless_pgtbl_walk();
ptep = __find_linux_pte(vcpu->arch.pgdir, hva, NULL, &shift);
/*
* If the PTE disappeared temporarily due to a THP
* collapse, just return and let the guest try again.
*/
if (!ptep) {
- local_irq_enable();
+ end_lockless_pgtbl_walk(IRQS_ENABLED);
if (page)
put_page(page);
return RESUME_GUEST;
}
pte = *ptep;
- local_irq_enable();
+ end_lockless_pgtbl_walk(IRQS_ENABLED);
/* If we're logging dirty pages, always map single pages */
large_enable = !(memslot->flags & KVM_MEM_LOG_DIRTY_PAGES);
@@ -980,10 +980,16 @@ int kvm_unmap_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
return 0;
}
+ /*
+ * 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.
+ */
ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
if (ptep && pte_present(*ptep))
kvmppc_unmap_pte(kvm, ptep, gpa, shift, memslot,
kvm->arch.lpid);
+
return 0;
}
@@ -1000,6 +1006,11 @@ int kvm_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE)
return ref;
+ /*
+ * 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.
+ */
ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
if (ptep && pte_present(*ptep) && pte_young(*ptep)) {
old = kvmppc_radix_update_pte(kvm, ptep, _PAGE_ACCESSED, 0,
@@ -1027,6 +1038,11 @@ int kvm_test_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE)
return ref;
+ /*
+ * 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.
+ */
ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
if (ptep && pte_present(*ptep) && pte_young(*ptep))
ref = 1;
@@ -1047,6 +1063,11 @@ static int kvm_radix_test_clear_dirty(struct kvm *kvm,
if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE)
return ret;
+ /*
+ * 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.
+ */
ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
if (ptep && pte_present(*ptep) && pte_dirty(*ptep)) {
ret = 1;
@@ -1063,6 +1084,7 @@ static int kvm_radix_test_clear_dirty(struct kvm *kvm,
1UL << shift);
spin_unlock(&kvm->mmu_lock);
}
+
return ret;
}
@@ -1108,6 +1130,12 @@ void kvmppc_radix_flush_memslot(struct kvm *kvm,
gpa = memslot->base_gfn << PAGE_SHIFT;
spin_lock(&kvm->mmu_lock);
for (n = memslot->npages; n; --n) {
+ /*
+ * 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.
+ */
ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
if (ptep && pte_present(*ptep))
kvmppc_unmap_pte(kvm, ptep, gpa, shift, memslot,
diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c
index ab6eeb8e753e..83c70c1557e4 100644
--- a/arch/powerpc/kvm/book3s_64_vio_hv.c
+++ b/arch/powerpc/kvm/book3s_64_vio_hv.c
@@ -453,10 +453,14 @@ static long kvmppc_rm_ua_to_hpa(struct kvm_vcpu *vcpu,
* to exit which will agains result in the below page table walk
* to finish.
*/
+ __begin_lockless_pgtbl_walk(false);
ptep = __find_linux_pte(vcpu->arch.pgdir, ua, NULL, &shift);
- if (!ptep || !pte_present(*ptep))
+ if (!ptep || !pte_present(*ptep)) {
+ __end_lockless_pgtbl_walk(0, false);
return -ENXIO;
+ }
pte = *ptep;
+ __end_lockless_pgtbl_walk(0, false);
if (!shift)
shift = PAGE_SHIFT;
--
2.24.1
next prev parent reply other threads:[~2020-02-06 3:08 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-06 3:08 [PATCH v6 00/11] Introduces new functions for tracking lockless pagetable walks Leonardo Bras
2020-02-06 3:08 ` Leonardo Bras
2020-02-06 3:08 ` [PATCH v6 01/11] asm-generic/pgtable: Adds generic functions to track lockless pgtable walks Leonardo Bras
2020-02-06 3:08 ` Leonardo Bras
2020-02-06 5:54 ` Christophe Leroy
2020-02-06 5:54 ` Christophe Leroy
2020-02-07 2:19 ` Leonardo Bras
2020-02-07 2:19 ` Leonardo Bras
2020-02-07 5:39 ` kbuild test robot
2020-02-07 5:39 ` kbuild test robot
2020-02-06 3:08 ` [PATCH v6 02/11] mm/gup: Use functions to track lockless pgtbl walks on gup_pgd_range Leonardo Bras
2020-02-06 3:08 ` Leonardo Bras
2020-02-06 3:25 ` Leonardo Bras
2020-02-06 3:25 ` Leonardo Bras
2020-02-07 22:54 ` John Hubbard
2020-02-07 22:54 ` John Hubbard
2020-02-17 20:55 ` Leonardo Bras
2020-02-17 20:55 ` Leonardo Bras
2020-10-15 14:46 ` Michal Suchánek
2020-10-16 3:27 ` Aneesh Kumar K.V
2020-02-07 1:19 ` kbuild test robot
2020-02-07 1:19 ` kbuild test robot
2020-02-07 8:01 ` kbuild test robot
2020-02-07 8:01 ` kbuild test robot
2020-02-06 3:08 ` [PATCH v6 03/11] powerpc/mm: Adds arch-specificic functions to track lockless pgtable walks Leonardo Bras
2020-02-06 3:08 ` Leonardo Bras
2020-02-06 5:46 ` Christophe Leroy
2020-02-06 5:46 ` Christophe Leroy
2020-02-07 4:38 ` Leonardo Bras
2020-02-07 4:38 ` Leonardo Bras
2020-02-17 20:32 ` Leonardo Bras
2020-02-17 20:32 ` Leonardo Bras
2020-02-06 3:08 ` [PATCH v6 04/11] powerpc/mce_power: Use functions to track lockless pgtbl walks Leonardo Bras
2020-02-06 3:08 ` Leonardo Bras
2020-02-06 5:48 ` Christophe Leroy
2020-02-06 5:48 ` Christophe Leroy
2020-02-07 4:00 ` Leonardo Bras
2020-02-07 4:00 ` Leonardo Bras
2020-02-06 3:08 ` [PATCH v6 05/11] powerpc/perf: " Leonardo Bras
2020-02-06 3:08 ` Leonardo Bras
2020-02-06 3:08 ` [PATCH v6 06/11] powerpc/mm/book3s64/hash: " Leonardo Bras
2020-02-06 3:08 ` Leonardo Bras
2020-02-06 6:06 ` Christophe Leroy
2020-02-06 6:06 ` Christophe Leroy
2020-02-07 3:49 ` Leonardo Bras
2020-02-07 3:49 ` Leonardo Bras
2020-02-06 3:08 ` [PATCH v6 07/11] powerpc/kvm/e500: " Leonardo Bras
2020-02-06 3:08 ` Leonardo Bras
2020-02-06 6:18 ` Christophe Leroy
2020-02-06 6:18 ` Christophe Leroy
2020-02-07 3:10 ` Leonardo Bras
2020-02-07 3:10 ` Leonardo Bras
2020-02-06 3:08 ` [PATCH v6 08/11] powerpc/kvm/book3s_hv: " Leonardo Bras
2020-02-06 3:08 ` Leonardo Bras
2020-02-06 3:08 ` Leonardo Bras [this message]
2020-02-06 3:08 ` [PATCH v6 09/11] powerpc/kvm/book3s_64: " Leonardo Bras
2020-02-06 3:08 ` [PATCH v6 10/11] powerpc/mm: Adds counting method to track lockless pagetable walks Leonardo Bras
2020-02-06 3:08 ` Leonardo Bras
2020-02-06 6:23 ` Christophe Leroy
2020-02-06 6:23 ` Christophe Leroy
2020-02-07 1:56 ` Leonardo Bras
2020-02-07 1:56 ` Leonardo Bras
2020-02-06 3:09 ` [PATCH v6 11/11] powerpc/mm/book3s64/pgtable: Uses counting method to skip serializing Leonardo Bras
2020-02-06 3:09 ` Leonardo Bras
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