From: Quentin Perret <qperret@google.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>
Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE"
<devicetree@vger.kernel.org>,
android-kvm@google.com, open list <linux-kernel@vger.kernel.org>,
kernel-team@android.com,
"open list:KERNEL VIRTUAL MACHINE FOR ARM64 \(KVM/arm64\)"
<kvmarm@lists.cs.columbia.edu>,
"moderated list:ARM64 PORT \(AARCH64 ARCHITECTURE\)"
<linux-arm-kernel@lists.infradead.org>
Subject: [RFC PATCH 03/27] KVM: arm64: Add standalone ticket spinlock implementation for use at hyp
Date: Tue, 17 Nov 2020 18:15:43 +0000 [thread overview]
Message-ID: <20201117181607.1761516-4-qperret@google.com> (raw)
In-Reply-To: <20201117181607.1761516-1-qperret@google.com>
From: Will Deacon <will@kernel.org>
We will soon need to synchronise multiple CPUs in the hyp text at EL2.
The qspinlock-based locking used by the host is overkill for this purpose
and requires a working "percpu" implementation for the MCS nodes.
Implement a simple ticket locking scheme based heavily on the code removed
by c11090474d70 ("arm64: locking: Replace ticket lock implementation with
qspinlock").
[ qperret: removed the __KVM_NVHE_HYPERVISOR__ build-time check from
spinlock.h ]
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
---
arch/arm64/kvm/hyp/include/nvhe/spinlock.h | 95 ++++++++++++++++++++++
arch/arm64/kvm/hyp/include/nvhe/util.h | 25 ++++++
2 files changed, 120 insertions(+)
create mode 100644 arch/arm64/kvm/hyp/include/nvhe/spinlock.h
create mode 100644 arch/arm64/kvm/hyp/include/nvhe/util.h
diff --git a/arch/arm64/kvm/hyp/include/nvhe/spinlock.h b/arch/arm64/kvm/hyp/include/nvhe/spinlock.h
new file mode 100644
index 000000000000..bbfe2cbd9f62
--- /dev/null
+++ b/arch/arm64/kvm/hyp/include/nvhe/spinlock.h
@@ -0,0 +1,95 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * A stand-alone ticket spinlock implementation, primarily for use by the
+ * non-VHE hypervisor code running at EL2.
+ *
+ * Copyright (C) 2020 Google LLC
+ * Author: Will Deacon <will@kernel.org>
+ *
+ * Heavily based on the implementation removed by c11090474d70 which was:
+ * Copyright (C) 2012 ARM Ltd.
+ */
+
+#ifndef __ARM64_KVM_HYP_SPINLOCK_H__
+#define __ARM64_KVM_HYP_SPINLOCK_H__
+
+#include <asm/alternative.h>
+
+typedef union hyp_spinlock {
+ u32 __val;
+ struct {
+#ifdef __AARCH64EB__
+ u16 next, owner;
+#else
+ u16 owner, next;
+#endif
+ };
+} hyp_spinlock_t;
+
+#define hyp_spin_lock_init(l) \
+do { \
+ *(l) = (hyp_spinlock_t){ .__val = 0 }; \
+} while (0)
+
+static inline void hyp_spin_lock(hyp_spinlock_t *lock)
+{
+ u32 tmp;
+ hyp_spinlock_t lockval, newval;
+
+ asm volatile(
+ /* Atomically increment the next ticket. */
+ ALTERNATIVE(
+ /* LL/SC */
+" prfm pstl1strm, %3\n"
+"1: ldaxr %w0, %3\n"
+" add %w1, %w0, #(1 << 16)\n"
+" stxr %w2, %w1, %3\n"
+" cbnz %w2, 1b\n",
+ /* LSE atomics */
+" .arch_extension lse\n"
+" mov %w2, #(1 << 16)\n"
+" ldadda %w2, %w0, %3\n"
+ __nops(3),
+ ARM64_HAS_LSE_ATOMICS)
+
+ /* Did we get the lock? */
+" eor %w1, %w0, %w0, ror #16\n"
+" cbz %w1, 3f\n"
+ /*
+ * No: spin on the owner. Send a local event to avoid missing an
+ * unlock before the exclusive load.
+ */
+" sevl\n"
+"2: wfe\n"
+" ldaxrh %w2, %4\n"
+" eor %w1, %w2, %w0, lsr #16\n"
+" cbnz %w1, 2b\n"
+ /* We got the lock. Critical section starts here. */
+"3:"
+ : "=&r" (lockval), "=&r" (newval), "=&r" (tmp), "+Q" (*lock)
+ : "Q" (lock->owner)
+ : "memory");
+}
+
+static inline void hyp_spin_unlock(hyp_spinlock_t *lock)
+{
+ u64 tmp;
+
+ asm volatile(
+ ALTERNATIVE(
+ /* LL/SC */
+ " ldrh %w1, %0\n"
+ " add %w1, %w1, #1\n"
+ " stlrh %w1, %0",
+ /* LSE atomics */
+ " .arch_extension lse\n"
+ " mov %w1, #1\n"
+ " staddlh %w1, %0\n"
+ __nops(1),
+ ARM64_HAS_LSE_ATOMICS)
+ : "=Q" (lock->owner), "=&r" (tmp)
+ :
+ : "memory");
+}
+
+#endif /* __ARM64_KVM_HYP_SPINLOCK_H__ */
diff --git a/arch/arm64/kvm/hyp/include/nvhe/util.h b/arch/arm64/kvm/hyp/include/nvhe/util.h
new file mode 100644
index 000000000000..9c58cc436a83
--- /dev/null
+++ b/arch/arm64/kvm/hyp/include/nvhe/util.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Standalone re-implementations of kernel interfaces for use at EL2.
+ * Copyright (C) 2020 Google LLC
+ * Author: Will Deacon <will@kernel.org>
+ */
+
+#ifndef __KVM_NVHE_HYPERVISOR__
+#error "Attempt to include nVHE code outside of EL2 object"
+#endif
+
+#ifndef __ARM64_KVM_NVHE_UTIL_H__
+#define __ARM64_KVM_NVHE_UTIL_H__
+
+/* Locking (hyp_spinlock_t) */
+#include <nvhe/spinlock.h>
+
+#undef spin_lock_init
+#define spin_lock_init hyp_spin_lock_init
+#undef spin_lock
+#define spin_lock hyp_spin_lock
+#undef spin_unlock
+#define spin_unlock hyp_spin_unlock
+
+#endif /* __ARM64_KVM_NVHE_UTIL_H__ */
--
2.29.2.299.gdc1121823c-goog
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next prev parent reply other threads:[~2020-11-17 18:16 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-17 18:15 [RFC PATCH 00/27] KVM/arm64: A stage 2 for the host Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 01/27] arm64: lib: Annotate {clear, copy}_page() as position-independent Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 02/27] KVM: arm64: Link position-independent string routines into .hyp.text Quentin Perret
2020-11-23 12:34 ` David Brazdil
2020-11-23 14:06 ` Quentin Perret
2020-11-17 18:15 ` Quentin Perret [this message]
2020-11-17 18:15 ` [RFC PATCH 04/27] KVM: arm64: Initialize kvm_nvhe_init_params early Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 05/27] KVM: arm64: Avoid free_page() in page-table allocator Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 06/27] KVM: arm64: Factor memory allocation out of pgtable.c Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 07/27] KVM: arm64: Introduce a BSS section for use at Hyp Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 08/27] KVM: arm64: Make kvm_call_hyp() a function call " Quentin Perret
2020-11-23 12:51 ` David Brazdil
2020-11-17 18:15 ` [RFC PATCH 09/27] KVM: arm64: Allow using kvm_nvhe_sym() in hyp code Quentin Perret
2020-11-23 12:57 ` David Brazdil
2020-11-23 14:02 ` Quentin Perret
2020-11-23 14:54 ` David Brazdil
2020-11-17 18:15 ` [RFC PATCH 10/27] KVM: arm64: Introduce an early Hyp page allocator Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 11/27] KVM: arm64: Stub CONFIG_DEBUG_LIST at Hyp Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 12/27] KVM: arm64: Introduce a Hyp buddy page allocator Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 13/27] KVM: arm64: Enable access to sanitized CPU features at EL2 Quentin Perret
2020-11-23 10:55 ` Fuad Tabba
2020-11-23 13:51 ` Quentin Perret
2020-11-23 13:22 ` David Brazdil
2020-11-23 14:39 ` Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 14/27] KVM: arm64: Factor out vector address calculation Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 15/27] of/fdt: Introduce early_init_dt_add_memory_hyp() Quentin Perret
2020-11-17 19:44 ` Rob Herring
2020-11-18 9:25 ` Quentin Perret
2020-11-18 14:31 ` Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 16/27] KVM: arm64: Prepare Hyp memory protection Quentin Perret
2020-12-03 12:57 ` Fuad Tabba
2020-12-04 18:01 ` Quentin Perret
2020-12-07 10:20 ` Will Deacon
2020-12-07 11:05 ` Mark Rutland
2020-12-07 11:10 ` Will Deacon
2020-12-07 11:14 ` Fuad Tabba
2020-12-07 11:16 ` Fuad Tabba
2020-12-07 11:58 ` Quentin Perret
2020-12-07 13:54 ` Marc Zyngier
2020-12-07 14:17 ` Quentin Perret
2020-12-07 13:40 ` Will Deacon
2020-12-07 14:11 ` Quentin Perret
2020-12-08 9:40 ` Will Deacon
2020-11-17 18:15 ` [RFC PATCH 17/27] KVM: arm64: Elevate Hyp mappings creation at EL2 Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 18/27] KVM: arm64: Use kvm_arch for stage 2 pgtable Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 19/27] KVM: arm64: Use kvm_arch in kvm_s2_mmu Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 20/27] KVM: arm64: Set host stage 2 using kvm_nvhe_init_params Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 21/27] KVM: arm64: Refactor kvm_arm_setup_stage2() Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 22/27] KVM: arm64: Refactor __load_guest_stage2() Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 23/27] KVM: arm64: Refactor __populate_fault_info() Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 24/27] KVM: arm64: Make memcache anonymous in pgtable allocator Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 25/27] KVM: arm64: Reserve memory for host stage 2 Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 26/27] KVM: arm64: Sort the memblock regions list Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 27/27] KVM: arm64: Wrap the host with a stage 2 Quentin Perret
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