From: Steven Price <steven.price@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>
Cc: Steven Price <steven.price@arm.com>,
James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Dave Martin <Dave.Martin@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
qemu-devel@nongnu.org, Juan Quintela <quintela@redhat.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Richard Henderson <richard.henderson@linaro.org>,
Peter Maydell <peter.maydell@linaro.org>,
Haibo Xu <Haibo.Xu@arm.com>, Andrew Jones <drjones@redhat.com>
Subject: [PATCH v10 1/6] arm64: mte: Sync tags for pages where PTE is untagged
Date: Fri, 12 Mar 2021 15:18:57 +0000 [thread overview]
Message-ID: <20210312151902.17853-2-steven.price@arm.com> (raw)
In-Reply-To: <20210312151902.17853-1-steven.price@arm.com>
A KVM guest could store tags in a page even if the VMM hasn't mapped
the page with PROT_MTE. So when restoring pages from swap we will
need to check to see if there are any saved tags even if !pte_tagged().
However don't check pages which are !pte_valid_user() as these will
not have been swapped out.
Signed-off-by: Steven Price <steven.price@arm.com>
---
arch/arm64/include/asm/pgtable.h | 2 +-
arch/arm64/kernel/mte.c | 16 ++++++++++++----
2 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index e17b96d0e4b5..84166625c989 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -312,7 +312,7 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
__sync_icache_dcache(pte);
if (system_supports_mte() &&
- pte_present(pte) && pte_tagged(pte) && !pte_special(pte))
+ pte_present(pte) && pte_valid_user(pte) && !pte_special(pte))
mte_sync_tags(ptep, pte);
__check_racy_pte_update(mm, ptep, pte);
diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index b3c70a612c7a..e016ab57ea36 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -26,17 +26,23 @@ u64 gcr_kernel_excl __ro_after_init;
static bool report_fault_once = true;
-static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap)
+static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap,
+ bool pte_is_tagged)
{
pte_t old_pte = READ_ONCE(*ptep);
if (check_swap && is_swap_pte(old_pte)) {
swp_entry_t entry = pte_to_swp_entry(old_pte);
- if (!non_swap_entry(entry) && mte_restore_tags(entry, page))
+ if (!non_swap_entry(entry) && mte_restore_tags(entry, page)) {
+ set_bit(PG_mte_tagged, &page->flags);
return;
+ }
}
+ if (!pte_is_tagged || test_and_set_bit(PG_mte_tagged, &page->flags))
+ return;
+
page_kasan_tag_reset(page);
/*
* We need smp_wmb() in between setting the flags and clearing the
@@ -54,11 +60,13 @@ void mte_sync_tags(pte_t *ptep, pte_t pte)
struct page *page = pte_page(pte);
long i, nr_pages = compound_nr(page);
bool check_swap = nr_pages == 1;
+ bool pte_is_tagged = pte_tagged(pte);
/* if PG_mte_tagged is set, tags have already been initialised */
for (i = 0; i < nr_pages; i++, page++) {
- if (!test_and_set_bit(PG_mte_tagged, &page->flags))
- mte_sync_page_tags(page, ptep, check_swap);
+ if (!test_bit(PG_mte_tagged, &page->flags))
+ mte_sync_page_tags(page, ptep, check_swap,
+ pte_is_tagged);
}
}
--
2.20.1
next prev parent reply other threads:[~2021-03-12 15:20 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-12 15:18 [PATCH v10 0/6] MTE support for KVM guest Steven Price
2021-03-12 15:18 ` Steven Price [this message]
2021-03-26 18:56 ` [PATCH v10 1/6] arm64: mte: Sync tags for pages where PTE is untagged Catalin Marinas
2021-03-29 15:55 ` Steven Price
2021-03-30 10:13 ` Catalin Marinas
2021-03-31 10:09 ` Steven Price
2021-03-12 15:18 ` [PATCH v10 2/6] arm64: kvm: Introduce MTE VM feature Steven Price
2021-03-27 15:23 ` Catalin Marinas
2021-03-28 12:21 ` Catalin Marinas
2021-03-29 16:06 ` Steven Price
2021-03-30 10:30 ` Catalin Marinas
2021-03-31 7:34 ` David Hildenbrand
2021-03-31 9:21 ` Catalin Marinas
2021-03-31 9:32 ` David Hildenbrand
2021-03-31 10:41 ` Steven Price
2021-03-31 14:14 ` David Hildenbrand
2021-03-31 18:43 ` Catalin Marinas
2021-04-07 10:20 ` Steven Price
2021-04-07 15:14 ` Catalin Marinas
2021-04-07 15:30 ` David Hildenbrand
2021-04-07 15:52 ` Steven Price
2021-04-08 14:18 ` Catalin Marinas
2021-04-08 18:16 ` David Hildenbrand
2021-04-08 18:21 ` Catalin Marinas
2021-03-12 15:18 ` [PATCH v10 3/6] arm64: kvm: Save/restore MTE registers Steven Price
2021-03-12 15:19 ` [PATCH v10 4/6] arm64: kvm: Expose KVM_ARM_CAP_MTE Steven Price
2021-03-12 15:19 ` [PATCH v10 5/6] KVM: arm64: ioctl to fetch/store tags in a guest Steven Price
2021-03-12 15:19 ` [PATCH v10 6/6] KVM: arm64: Document MTE capability and ioctl Steven Price
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