[PATCH v2 08/28] ARM: KVM: Add TLB invalidation code

On 09/02/16 18:42, Christoffer Dall wrote:

On Thu, Feb 04, 2016 at 11:00:25AM +0000, Marc Zyngier wrote:

quoted

Convert the TLB invalidation code to C, hooking it into the
build system whilst we're at it.

Signed-off-by: Marc Zyngier <redacted>
---
 arch/arm/kvm/Makefile     |  1 +
 arch/arm/kvm/hyp/Makefile |  5 ++++
 arch/arm/kvm/hyp/hyp.h    |  5 ++++
 arch/arm/kvm/hyp/tlb.c    | 71 +++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 82 insertions(+)
 create mode 100644 arch/arm/kvm/hyp/Makefile
 create mode 100644 arch/arm/kvm/hyp/tlb.c

diff --git a/arch/arm/kvm/Makefile b/arch/arm/kvm/Makefile
index c5eef02c..eb1bf43 100644
--- a/arch/arm/kvm/Makefile
+++ b/arch/arm/kvm/Makefile

@@ -17,6 +17,7 @@ AFLAGS_interrupts.o := -Wa,-march=armv7-a$(plus_virt)
 KVM := ../../../virt/kvm
 kvm-arm-y = $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o $(KVM)/vfio.o
 
+obj-$(CONFIG_KVM_ARM_HOST) += hyp/
 obj-y += kvm-arm.o init.o interrupts.o
 obj-y += arm.o handle_exit.o guest.o mmu.o emulate.o reset.o
 obj-y += coproc.o coproc_a15.o coproc_a7.o mmio.o psci.o perf.o

diff --git a/arch/arm/kvm/hyp/Makefile b/arch/arm/kvm/hyp/Makefile
new file mode 100644
index 0000000..36c760d
--- /dev/null
+++ b/arch/arm/kvm/hyp/Makefile

@@ -0,0 +1,5 @@
+#
+# Makefile for Kernel-based Virtual Machine module, HYP part
+#
+
+obj-$(CONFIG_KVM_ARM_HOST) += tlb.o

diff --git a/arch/arm/kvm/hyp/hyp.h b/arch/arm/kvm/hyp/hyp.h
index 727089f..5808bbd 100644
--- a/arch/arm/kvm/hyp/hyp.h
+++ b/arch/arm/kvm/hyp/hyp.h

@@ -42,4 +42,9 @@
 })
 #define read_sysreg(...)		__read_sysreg(__VA_ARGS__)
 
+#define VTTBR		__ACCESS_CP15_64(6, c2)
+#define ICIALLUIS	__ACCESS_CP15(c7, 0, c1, 0)
+#define TLBIALLIS	__ACCESS_CP15(c8, 0, c3, 0)
+#define TLBIALLNSNHIS	__ACCESS_CP15(c8, 4, c3, 4)
+
 #endif /* __ARM_KVM_HYP_H__ */

diff --git a/arch/arm/kvm/hyp/tlb.c b/arch/arm/kvm/hyp/tlb.c
new file mode 100644
index 0000000..993fe89
--- /dev/null
+++ b/arch/arm/kvm/hyp/tlb.c

@@ -0,0 +1,71 @@
+/*
+ * Original code:
+ * Copyright (C) 2012 - Virtual Open Systems and Columbia University
+ * Author: Christoffer Dall <c.dall@virtualopensystems.com>
+ *
+ * Mostly rewritten in C by Marc Zyngier <marc.zyngier@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "hyp.h"
+
+/**
+ * Flush per-VMID TLBs
+ *
+ * __kvm_tlb_flush_vmid(struct kvm *kvm);
+ *
+ * We rely on the hardware to broadcast the TLB invalidation to all CPUs
+ * inside the inner-shareable domain (which is the case for all v7
+ * implementations).  If we come across a non-IS SMP implementation, we'll
+ * have to use an IPI based mechanism. Until then, we stick to the simple
+ * hardware assisted version.
+ *
+ * As v7 does not support flushing per IPA, just nuke the whole TLB
+ * instead, ignoring the ipa value.
+ */
+static void __hyp_text __tlb_flush_vmid(struct kvm *kvm)
+{
+	dsb(ishst);
+
+	/* Switch to requested VMID */
+	kvm = kern_hyp_va(kvm);
+	write_sysreg(kvm->arch.vttbr, VTTBR);
+	isb();
+
+	write_sysreg(0, TLBIALLIS);
+	dsb(ish);
+	isb();
+
+	write_sysreg(0, VTTBR);
+}
+
+__alias(__tlb_flush_vmid) void __weak __kvm_tlb_flush_vmid(struct kvm *kvm);
+
+static void __hyp_text __tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa)
+{
+	__tlb_flush_vmid(kvm);
+}
+
+__alias(__tlb_flush_vmid_ipa) void __weak __kvm_tlb_flush_vmid_ipa(struct kvm *kvm,
+							    phys_addr_t ipa);
+
+static void __hyp_text __tlb_flush_vm_context(void)
+{
+	dsb(ishst);

do we need this initial dsb?

I'm a copy-paste muppet. I'll drop that.

quoted

+	write_sysreg(0, TLBIALLNSNHIS);
+	write_sysreg(0, ICIALLUIS);
+	dsb(ish);

we used to have an isb here, but we got rid of this because it's always
followed by eret?

Indeed. We were super extra cautious in the old code, and eret does the
right thing.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...