[PATCH v2 16/28] ARM: KVM: Add the new world switch implementation

Marc Zyngier
2016-02-04T11:00:33Z

The new world switch implementation is modeled after the arm64 one,
calling the various save/restore functions in turn, and having as
little state as possible.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
arch/arm/kvm/hyp/Makefile | 1 +
arch/arm/kvm/hyp/hyp.h | 7 +++
arch/arm/kvm/hyp/switch.c | 136 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 144 insertions(+)
create mode 100644 arch/arm/kvm/hyp/switch.c

diff --git a/arch/arm/kvm/hyp/Makefile b/arch/arm/kvm/hyp/Makefile
index c779690..cfab402 100644
--- a/arch/arm/kvm/hyp/Makefile
+++ b/arch/arm/kvm/hyp/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_KVM_ARM_HOST) += vgic-v2-sr.o
obj-$(CONFIG_KVM_ARM_HOST) += vfp.o
obj-$(CONFIG_KVM_ARM_HOST) += banked-sr.o
obj-$(CONFIG_KVM_ARM_HOST) += entry.o
+obj-$(CONFIG_KVM_ARM_HOST) += switch.o
diff --git a/arch/arm/kvm/hyp/hyp.h b/arch/arm/kvm/hyp/hyp.h
index b3f6ed2..2ca651f 100644
--- a/arch/arm/kvm/hyp/hyp.h
+++ b/arch/arm/kvm/hyp/hyp.h
@@ -60,11 +60,16 @@
#define CNTV_CVAL __ACCESS_CP15_64(3, c14)
#define CNTVOFF __ACCESS_CP15_64(4, c14)

+#define MIDR __ACCESS_CP15(c0, 0, c0, 0)
#define CSSELR __ACCESS_CP15(c0, 2, c0, 0)
+#define VMIDR __ACCESS_CP15(c0, 4, c0, 0)
#define VMPIDR __ACCESS_CP15(c0, 4, c0, 5)
#define SCTLR __ACCESS_CP15(c1, 0, c0, 0)
#define CPACR __ACCESS_CP15(c1, 0, c0, 2)
+#define HCR __ACCESS_CP15(c1, 4, c1, 0)
+#define HDCR __ACCESS_CP15(c1, 4, c1, 1)
#define HCPTR __ACCESS_CP15(c1, 4, c1, 2)
+#define HSTR __ACCESS_CP15(c1, 4, c1, 3)
#define TTBCR __ACCESS_CP15(c2, 0, c0, 2)
#define DACR __ACCESS_CP15(c3, 0, c0, 0)
#define DFSR __ACCESS_CP15(c5, 0, c0, 0)
@@ -73,6 +78,7 @@
#define AIFSR __ACCESS_CP15(c5, 0, c1, 1)
#define DFAR __ACCESS_CP15(c6, 0, c0, 0)
#define IFAR __ACCESS_CP15(c6, 0, c0, 2)
+#define HDFAR __ACCESS_CP15(c6, 4, c0, 0)
#define ICIALLUIS __ACCESS_CP15(c7, 0, c1, 0)
#define TLBIALLIS __ACCESS_CP15(c8, 0, c3, 0)
#define TLBIALLNSNHIS __ACCESS_CP15(c8, 4, c3, 4)
@@ -85,6 +91,7 @@
#define TID_URW __ACCESS_CP15(c13, 0, c0, 2)
#define TID_URO __ACCESS_CP15(c13, 0, c0, 3)
#define TID_PRIV __ACCESS_CP15(c13, 0, c0, 4)
+#define HTPIDR __ACCESS_CP15(c13, 4, c0, 2)
#define CNTKCTL __ACCESS_CP15(c14, 0, c1, 0)
#define CNTV_CTL __ACCESS_CP15(c14, 0, c3, 1)
#define CNTHCTL __ACCESS_CP15(c14, 4, c1, 0)
diff --git a/arch/arm/kvm/hyp/switch.c b/arch/arm/kvm/hyp/switch.c
new file mode 100644
index 0000000..f715b0d
--- /dev/null
+++ b/arch/arm/kvm/hyp/switch.c
@@ -0,0 +1,136 @@
+/*
+ * Copyright (C) 2015 - ARM Ltd
+ * Author: 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 <asm/kvm_asm.h>
+#include "hyp.h"
+
+__asm__(".arch_extension virt");
+
+static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu, u32 *fpexc)
+{
+ u32 val;
+
+ /*
+ * We are about to set HCPTR.TCP10/11 to trap all floating point
+ * register accesses to HYP, however, the ARM ARM clearly states that
+ * traps are only taken to HYP if the operation would not otherwise
+ * trap to SVC. Therefore, always make sure that for 32-bit guests,
+ * we set FPEXC.EN to prevent traps to SVC, when setting the TCP bits.
+ */
+ val = read_sysreg(VFP_FPEXC);
+ *fpexc = val;
+ if (!(val & FPEXC_EN)) {
+ write_sysreg(val | FPEXC_EN, VFP_FPEXC);
+ isb();
+ }
+
+ write_sysreg(vcpu->arch.hcr | vcpu->arch.irq_lines, HCR);
+ /* Trap on AArch32 cp15 c15 accesses (EL1 or EL0) */
+ write_sysreg(HSTR_T(15), HSTR);
+ write_sysreg(HCPTR_TTA | HCPTR_TCP(10) | HCPTR_TCP(11), HCPTR);
+ val = read_sysreg(HDCR);
+ write_sysreg(val | HDCR_TPM | HDCR_TPMCR, HDCR);
+}
+
+static void __hyp_text __deactivate_traps(struct kvm_vcpu *vcpu)
+{
+ u32 val;
+
+ write_sysreg(0, HCR);
+ write_sysreg(0, HSTR);
+ val = read_sysreg(HDCR);
+ write_sysreg(val & ~(HDCR_TPM | HDCR_TPMCR), HDCR);
+ write_sysreg(0, HCPTR);
+}
+
+static void __hyp_text __activate_vm(struct kvm_vcpu *vcpu)
+{
+ struct kvm *kvm = kern_hyp_va(vcpu->kvm);
+ write_sysreg(kvm->arch.vttbr, VTTBR);
+ write_sysreg(vcpu->arch.midr, VMIDR);
+}
+
+static void __hyp_text __deactivate_vm(struct kvm_vcpu *vcpu)
+{
+ write_sysreg(0, VTTBR);
+ write_sysreg(read_sysreg(MIDR), VMIDR);
+}
+
+static void __hyp_text __vgic_save_state(struct kvm_vcpu *vcpu)
+{
+ __vgic_v2_save_state(vcpu);
+}
+
+static void __hyp_text __vgic_restore_state(struct kvm_vcpu *vcpu)
+{
+ __vgic_v2_restore_state(vcpu);
+}
+
+static int __hyp_text __guest_run(struct kvm_vcpu *vcpu)
+{
+ struct kvm_cpu_context *host_ctxt;
+ struct kvm_cpu_context *guest_ctxt;
+ bool fp_enabled;
+ u64 exit_code;
+ u32 fpexc;
+
+ vcpu = kern_hyp_va(vcpu);
+ write_sysreg(vcpu, HTPIDR);
+
+ host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
+ guest_ctxt = &vcpu->arch.ctxt;
+
+ __sysreg_save_state(host_ctxt);
+ __banked_save_state(host_ctxt);
+
+ __activate_traps(vcpu, &fpexc);
+ __activate_vm(vcpu);
+
+ __vgic_restore_state(vcpu);
+ __timer_restore_state(vcpu);
+
+ __sysreg_restore_state(guest_ctxt);
+ __banked_restore_state(guest_ctxt);
+
+ /* Jump in the fire! */
+ exit_code = __guest_enter(vcpu, host_ctxt);
+ /* And we're baaack! */
+
+ fp_enabled = __vfp_enabled();
+
+ __banked_save_state(guest_ctxt);
+ __sysreg_save_state(guest_ctxt);
+ __timer_save_state(vcpu);
+ __vgic_save_state(vcpu);
+
+ __deactivate_traps(vcpu);
+ __deactivate_vm(vcpu);
+
+ __banked_restore_state(host_ctxt);
+ __sysreg_restore_state(host_ctxt);
+
+ if (fp_enabled) {
+ __vfp_save_state(&guest_ctxt->vfp);
+ __vfp_restore_state(&host_ctxt->vfp);
+ }
+
+ write_sysreg(fpexc, VFP_FPEXC);
+
+ return exit_code;
+}
+
+__alias(__guest_run) int __weak __kvm_vcpu_run(struct kvm_vcpu *vcpu);
--
2.1.4