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: Mark Rutland <mark.rutland@arm.com>,
Peter Maydell <peter.maydell@linaro.org>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Andrew Jones <drjones@redhat.com>, Haibo Xu <Haibo.Xu@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
qemu-devel@nongnu.org, Dave Martin <Dave.Martin@arm.com>,
Juan Quintela <quintela@redhat.com>,
Richard Henderson <richard.henderson@linaro.org>,
linux-kernel@vger.kernel.org, Steven Price <steven.price@arm.com>,
James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH v10 2/6] arm64: kvm: Introduce MTE VM feature
Date: Fri, 12 Mar 2021 15:18:58 +0000 [thread overview]
Message-ID: <20210312151902.17853-3-steven.price@arm.com> (raw)
In-Reply-To: <20210312151902.17853-1-steven.price@arm.com>
Add a new VM feature 'KVM_ARM_CAP_MTE' which enables memory tagging
for a VM. This will expose the feature to the guest and automatically
tag memory pages touched by the VM as PG_mte_tagged (and clear the tag
storage) to ensure that the guest cannot see stale tags, and so that
the tags are correctly saved/restored across swap.
Actually exposing the new capability to user space happens in a later
patch.
Signed-off-by: Steven Price <steven.price@arm.com>
---
arch/arm64/include/asm/kvm_emulate.h | 3 +++
arch/arm64/include/asm/kvm_host.h | 3 +++
arch/arm64/kvm/hyp/exception.c | 3 ++-
arch/arm64/kvm/mmu.c | 16 ++++++++++++++++
arch/arm64/kvm/sys_regs.c | 3 +++
include/uapi/linux/kvm.h | 1 +
6 files changed, 28 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index f612c090f2e4..6bf776c2399c 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -84,6 +84,9 @@ static inline void vcpu_reset_hcr(struct kvm_vcpu *vcpu)
if (cpus_have_const_cap(ARM64_MISMATCHED_CACHE_TYPE) ||
vcpu_el1_is_32bit(vcpu))
vcpu->arch.hcr_el2 |= HCR_TID2;
+
+ if (kvm_has_mte(vcpu->kvm))
+ vcpu->arch.hcr_el2 |= HCR_ATA;
}
static inline unsigned long *vcpu_hcr(struct kvm_vcpu *vcpu)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 3d10e6527f7d..1170ee137096 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -132,6 +132,8 @@ struct kvm_arch {
u8 pfr0_csv2;
u8 pfr0_csv3;
+ /* Memory Tagging Extension enabled for the guest */
+ bool mte_enabled;
};
struct kvm_vcpu_fault_info {
@@ -767,6 +769,7 @@ bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu);
#define kvm_arm_vcpu_sve_finalized(vcpu) \
((vcpu)->arch.flags & KVM_ARM64_VCPU_SVE_FINALIZED)
+#define kvm_has_mte(kvm) (system_supports_mte() && (kvm)->arch.mte_enabled)
#define kvm_vcpu_has_pmu(vcpu) \
(test_bit(KVM_ARM_VCPU_PMU_V3, (vcpu)->arch.features))
diff --git a/arch/arm64/kvm/hyp/exception.c b/arch/arm64/kvm/hyp/exception.c
index 73629094f903..56426565600c 100644
--- a/arch/arm64/kvm/hyp/exception.c
+++ b/arch/arm64/kvm/hyp/exception.c
@@ -112,7 +112,8 @@ static void enter_exception64(struct kvm_vcpu *vcpu, unsigned long target_mode,
new |= (old & PSR_C_BIT);
new |= (old & PSR_V_BIT);
- // TODO: TCO (if/when ARMv8.5-MemTag is exposed to guests)
+ if (kvm_has_mte(vcpu->kvm))
+ new |= PSR_TCO_BIT;
new |= (old & PSR_DIT_BIT);
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 77cb2d28f2a4..b31b7a821f90 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -879,6 +879,22 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
if (vma_pagesize == PAGE_SIZE && !force_pte)
vma_pagesize = transparent_hugepage_adjust(memslot, hva,
&pfn, &fault_ipa);
+
+ if (fault_status != FSC_PERM && kvm_has_mte(kvm) && pfn_valid(pfn)) {
+ /*
+ * VM will be able to see the page's tags, so we must ensure
+ * they have been initialised. if PG_mte_tagged is set, tags
+ * have already been initialised.
+ */
+ struct page *page = pfn_to_page(pfn);
+ unsigned long i, nr_pages = vma_pagesize >> PAGE_SHIFT;
+
+ for (i = 0; i < nr_pages; i++, page++) {
+ if (!test_and_set_bit(PG_mte_tagged, &page->flags))
+ mte_clear_page_tags(page_address(page));
+ }
+ }
+
if (writable)
prot |= KVM_PGTABLE_PROT_W;
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 4f2f1e3145de..18c87500a7a8 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1047,6 +1047,9 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu,
break;
case SYS_ID_AA64PFR1_EL1:
val &= ~FEATURE(ID_AA64PFR1_MTE);
+ if (kvm_has_mte(vcpu->kvm))
+ val |= FIELD_PREP(FEATURE(ID_AA64PFR1_MTE),
+ ID_AA64PFR1_MTE);
break;
case SYS_ID_AA64ISAR1_EL1:
if (!vcpu_has_ptrauth(vcpu))
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index f6afee209620..6dc16c09a2d1 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1078,6 +1078,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_DIRTY_LOG_RING 192
#define KVM_CAP_X86_BUS_LOCK_EXIT 193
#define KVM_CAP_PPC_DAWR1 194
+#define KVM_CAP_ARM_MTE 195
#ifdef KVM_CAP_IRQ_ROUTING
--
2.20.1
next prev parent reply other threads:[~2021-03-12 15:30 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 ` [PATCH v10 1/6] arm64: mte: Sync tags for pages where PTE is untagged Steven Price
2021-03-26 18:56 ` 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 ` Steven Price [this message]
2021-03-27 15:23 ` [PATCH v10 2/6] arm64: kvm: Introduce MTE VM feature 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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