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 08/11] powerpc/kvm/book3s_hv: Use functions to track lockless pgtbl walks
Date: Thu, 6 Feb 2020 00:08:57 -0300 [thread overview]
Message-ID: <20200206030900.147032-9-leonardo@linux.ibm.com> (raw)
Message-ID: <20200206030857.-3uiAKD-t77a5TRIRxqUjaTkmrU_qZOwhDvFeLUTQmk@z> (raw)
In-Reply-To: <20200206030900.147032-1-leonardo@linux.ibm.com>
Applies the new functions for tracking 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 | 28 ++++++++++++++++++----------
2 files changed, 38 insertions(+), 12 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c
index dc97e5be76f6..a398061d5778 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..fd4d8f174f09 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;
@@ -252,8 +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);
+ irq_mask = __begin_lockless_pgtbl_walk(!realmode);
+
/*
* If called in real mode we have MSR_EE = 0. Otherwise
* we disable irq above.
@@ -272,8 +272,7 @@ 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(irq_mask, !realmode);
return H_PARAMETER;
}
pte = kvmppc_read_update_linux_pte(ptep, writing);
@@ -287,8 +286,6 @@ 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 +299,10 @@ 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(irq_mask, !realmode);
return H_PARAMETER;
+ }
/*
* Allow guest to map emulated device memory as
* uncacheable, but actually make it cacheable.
@@ -311,6 +310,7 @@ 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(irq_mask, !realmode);
/* Find and lock the HPTEG slot to use */
do_insert:
@@ -907,11 +907,19 @@ 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(false);
ptep = __find_linux_pte(vcpu->arch.pgdir, hva, NULL, &shift);
- if (!ptep)
+ if (!ptep) {
+ __end_lockless_pgtbl_walk(0, false);
return H_TOO_HARD;
+ }
pte = kvmppc_read_update_linux_pte(ptep, writing);
+ __end_lockless_pgtbl_walk(0, false);
+
if (!pte_present(pte))
return H_TOO_HARD;
--
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 ` Leonardo Bras [this message]
2020-02-06 3:08 ` [PATCH v6 08/11] powerpc/kvm/book3s_hv: " Leonardo Bras
2020-02-06 3:08 ` [PATCH v6 09/11] powerpc/kvm/book3s_64: " Leonardo Bras
2020-02-06 3:08 ` 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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