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 08/11] powerpc/kvm/book3s_hv: Applies counting method to monitor lockless pgtbl walks
Date: Fri, 27 Sep 2019 20:40:05 -0300 [thread overview]
Message-ID: <20190927234008.11513-9-leonardo@linux.ibm.com> (raw)
In-Reply-To: <20190927234008.11513-1-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).
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 | 18 ++++++++++++++----
2 files changed, 34 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c
index 735e0ac6f5b2..5a641b559de7 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 63e0ce91e29d..2076a7ac230a 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -252,6 +252,7 @@ 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.
*/
+ start_lockless_pgtbl_walk(kvm->mm);
if (!realmode)
local_irq_save(irq_flags);
/*
@@ -287,8 +288,6 @@ 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;
@@ -311,6 +310,9 @@ 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;
}
+ if (!realmode)
+ local_irq_restore(irq_flags);
+ end_lockless_pgtbl_walk(kvm->mm);
/* Find and lock the HPTEG slot to use */
do_insert:
@@ -885,11 +887,19 @@ 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.
+ */
+ 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
next prev parent reply other threads:[~2019-09-27 23:41 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-27 23:39 [PATCH v4 00/11] Introduces new count-based method for monitoring lockless pagetable walks Leonardo Bras
2019-09-27 23:39 ` [PATCH v4 01/11] powerpc/mm: Adds counting method to monitor lockless pgtable walks Leonardo Bras
2019-09-29 22:40 ` John Hubbard
2019-09-29 23:17 ` John Hubbard
2019-09-30 15:14 ` Leonardo Bras
2019-09-30 17:57 ` John Hubbard
2019-09-30 18:42 ` Leonardo Bras
2019-09-30 21:47 ` John Hubbard
2019-10-01 18:39 ` Leonardo Bras
2019-10-01 18:52 ` John Hubbard
2019-09-27 23:39 ` [PATCH v4 02/11] asm-generic/pgtable: Adds dummy functions " Leonardo Bras
2019-09-27 23:40 ` [PATCH v4 03/11] mm/gup: Applies counting method to monitor gup_pgd_range Leonardo Bras
2019-09-30 11:09 ` Kirill A. Shutemov
2019-09-30 14:27 ` Leonardo Bras
2019-09-30 21:51 ` John Hubbard
2019-10-01 17:56 ` Leonardo Bras
2019-10-01 19:04 ` John Hubbard
2019-10-01 19:40 ` Leonardo Bras
2019-09-27 23:40 ` [PATCH v4 04/11] powerpc/mce_power: Applies counting method to monitor lockless pgtbl walks Leonardo Bras
2019-09-27 23:40 ` [PATCH v4 05/11] powerpc/perf: " Leonardo Bras
2019-09-27 23:40 ` [PATCH v4 06/11] powerpc/mm/book3s64/hash: " Leonardo Bras
2019-09-27 23:40 ` [PATCH v4 07/11] powerpc/kvm/e500: " Leonardo Bras
2019-09-27 23:40 ` Leonardo Bras [this message]
2019-09-27 23:40 ` [PATCH v4 09/11] powerpc/kvm/book3s_64: " Leonardo Bras
2019-09-27 23:40 ` [PATCH v4 10/11] powerpc/book3s_64: Enables counting method to monitor lockless pgtbl walk Leonardo Bras
2019-09-27 23:40 ` [PATCH v4 11/11] powerpc/mm/book3s64/pgtable: Uses counting method to skip serializing Leonardo Bras
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190927234008.11513-9-leonardo@linux.ibm.com \
--to=leonardo@linux.ibm.com \
--cc=akpm@linux-foundation.org \
--cc=allison@lohutok.net \
--cc=aneesh.kumar@linux.ibm.com \
--cc=arnd@arndb.de \
--cc=benh@kernel.crashing.org \
--cc=christophe.leroy@c-s.fr \
--cc=dan.j.williams@intel.com \
--cc=ganeshgr@linux.ibm.com \
--cc=gregkh@linuxfoundation.org \
--cc=ira.weiny@intel.com \
--cc=jgg@ziepe.ca \
--cc=jhubbard@nvidia.com \
--cc=keith.busch@intel.com \
--cc=kvm-ppc@vger.kernel.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mahesh@linux.vnet.ibm.com \
--cc=mpe@ellerman.id.au \
--cc=npiggin@gmail.com \
--cc=paulus@samba.org \
--cc=rppt@linux.ibm.com \
--cc=tglx@linutronix.de \
--cc=yuehaibing@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).