[PATCH 4/4] KVM: arm64: Upgrade VMID accesses to {READ,WRITE}_ONCE
From: Will Deacon <will@kernel.org>
Date: 2021-08-06 11:34:30
Also in:
kvmarm, linux-arm-kernel
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
From: Marc Zyngier <maz@kernel.org>
Since TLB invalidation can run in parallel with VMID allocation,
we need to be careful and avoid any sort of load/store tearing.
Use {READ,WRITE}_ONCE consistently to avoid any surprise.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jade Alglave <redacted>
Cc: Shameer Kolothum <redacted>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/include/asm/kvm_mmu.h | 7 ++++++-
arch/arm64/kvm/arm.c | 2 +-
arch/arm64/kvm/hyp/nvhe/mem_protect.c | 4 ++--
arch/arm64/kvm/mmu.c | 2 +-
4 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 934ef0deff9f..5828dd8fa738 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h@@ -252,6 +252,11 @@ static inline int kvm_write_guest_lock(struct kvm *kvm, gpa_t gpa, #define kvm_phys_to_vttbr(addr) phys_to_ttbr(addr) +/* + * When this is (directly or indirectly) used on the TLB invalidation + * path, we rely on a previously issued DSB so that page table updates + * and VMID reads are correctly ordered. + */ static __always_inline u64 kvm_get_vttbr(struct kvm_s2_mmu *mmu) { struct kvm_vmid *vmid = &mmu->vmid;
@@ -259,7 +264,7 @@ static __always_inline u64 kvm_get_vttbr(struct kvm_s2_mmu *mmu) u64 cnp = system_supports_cnp() ? VTTBR_CNP_BIT : 0; baddr = mmu->pgd_phys; - vmid_field = (u64)vmid->vmid << VTTBR_VMID_SHIFT; + vmid_field = (u64)READ_ONCE(vmid->vmid) << VTTBR_VMID_SHIFT; return kvm_phys_to_vttbr(baddr) | vmid_field | cnp; }
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index e9a2b8f27792..658f76067f46 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c@@ -571,7 +571,7 @@ static void update_vmid(struct kvm_vmid *vmid) kvm_call_hyp(__kvm_flush_vm_context); } - vmid->vmid = kvm_next_vmid; + WRITE_ONCE(vmid->vmid, kvm_next_vmid); kvm_next_vmid++; kvm_next_vmid &= (1 << kvm_get_vmid_bits()) - 1;
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index d4e74ca7f876..55ae97a144b8 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c@@ -109,8 +109,8 @@ int kvm_host_prepare_stage2(void *pgt_pool_base) mmu->pgd_phys = __hyp_pa(host_kvm.pgt.pgd); mmu->arch = &host_kvm.arch; mmu->pgt = &host_kvm.pgt; - mmu->vmid.vmid_gen = 0; - mmu->vmid.vmid = 0; + WRITE_ONCE(mmu->vmid.vmid_gen, 0); + WRITE_ONCE(mmu->vmid.vmid, 0); return 0; }
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 3155c9e778f0..b1a6eaec28ff 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c@@ -485,7 +485,7 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu) mmu->arch = &kvm->arch; mmu->pgt = pgt; mmu->pgd_phys = __pa(pgt->pgd); - mmu->vmid.vmid_gen = 0; + WRITE_ONCE(mmu->vmid.vmid_gen, 0); return 0; out_destroy_pgtable:
--
2.32.0.605.g8dce9f2422-goog