[RFC 39/55] KVM: arm/arm64: Add mmu context for the nesting

Jintack Lim
2017-01-09T06:24:35Z

Add the shadow stage-2 MMU context to be used for the nesting, but don't
do anything with it yet.

The host hypervisor maintains mmu structures for each nested VM. When
entering a nested VM, the host hypervisor searches for the nested VM's
mmu using vmid as a key. Note that this vmid is from the guest
hypervisor's point of view.

Signed-off-by: Jintack Lim <jintack@cs.columbia.edu>
---
arch/arm/include/asm/kvm_host.h | 3 ++
arch/arm/kvm/arm.c | 1 +
arch/arm64/include/asm/kvm_emulate.h | 13 ++++-----
arch/arm64/include/asm/kvm_host.h | 19 +++++++++++++
arch/arm64/include/asm/kvm_mmu.h | 31 ++++++++++++++++++++
arch/arm64/kvm/Makefile | 1 +
arch/arm64/kvm/context.c | 2 +-
arch/arm64/kvm/mmu-nested.c | 55 ++++++++++++++++++++++++++++++++++++
8 files changed, 116 insertions(+), 9 deletions(-)
create mode 100644 arch/arm64/kvm/mmu-nested.c

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index da45394..fbde48d 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -82,6 +82,9 @@ struct kvm_arch {
* here.
*/

+ /* Never used on arm but added to be compatible with arm64 */
+ struct list_head nested_mmu_list;
+
/* Interrupt controller */
struct vgic_dist vgic;
int max_vcpus;
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 371b38e7..147df97 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -146,6 +146,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
/* Mark the initial VMID generation invalid */
kvm->arch.mmu.vmid.vmid_gen = 0;
kvm->arch.mmu.el2_vmid.vmid_gen = 0;
+ INIT_LIST_HEAD(&kvm->arch.nested_mmu_list);

/* The maximum number of VCPUs is limited by the host's GIC model */
kvm->arch.max_vcpus = vgic_present ?
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 94068e7..abad676 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -183,6 +183,11 @@ static inline bool vcpu_el2_imo_is_set(const struct kvm_vcpu *vcpu)
return (vcpu_el2_reg(vcpu, HCR_EL2) & HCR_IMO);
}

+static inline bool vcpu_nested_stage2_enabled(const struct kvm_vcpu *vcpu)
+{
+ return (vcpu_el2_reg(vcpu, HCR_EL2) & HCR_VM);
+}
+
static inline u32 kvm_vcpu_get_hsr(const struct kvm_vcpu *vcpu)
{
return vcpu->arch.fault.esr_el2;
@@ -363,12 +368,4 @@ static inline unsigned long vcpu_data_host_to_guest(struct kvm_vcpu *vcpu,
return data; /* Leave LE untouched */
}

-static inline struct kvm_s2_vmid *vcpu_get_active_vmid(struct kvm_vcpu *vcpu)
-{
- if (unlikely(vcpu_mode_el2(vcpu)))
- return &vcpu->kvm->arch.mmu.el2_vmid;
-
- return &vcpu->kvm->arch.mmu.vmid;
-}
-
#endif /* __ARM64_KVM_EMULATE_H__ */
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index b33d35d..23e2267 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -65,6 +65,22 @@ struct kvm_s2_mmu {
pgd_t *pgd;
};

+/* Per nested VM mmu structure */
+struct kvm_nested_s2_mmu {
+ struct kvm_s2_mmu mmu;
+
+ /*
+ * The vttbr value set by the guest hypervisor for this nested VM.
+ * vmid field is used as a key to search for this mmu structure among
+ * all nested VM mmu structures by the host hypervisor.
+ * baddr field is used to determine if we need to unmap stage 2
+ * shadow page tables.
+ */
+ u64 virtual_vttbr;
+
+ struct list_head list;
+};
+
struct kvm_arch {
/* Stage 2 paging state for the VM */
struct kvm_s2_mmu mmu;
@@ -80,6 +96,9 @@ struct kvm_arch {

/* Timer */
struct arch_timer_kvm timer;
+
+ /* Stage 2 shadow paging contexts for nested L2 VM */
+ struct list_head nested_mmu_list;
};

#define KVM_NR_MEM_OBJS 40
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index a504162..d1ef650 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -112,6 +112,7 @@
#include <asm/cacheflush.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
+#include <asm/kvm_emulate.h>

static inline unsigned long __kern_hyp_va(unsigned long v)
{
@@ -323,6 +324,21 @@ static inline unsigned int kvm_get_vmid_bits(void)
return (cpuid_feature_extract_unsigned_field(reg, ID_AA64MMFR1_VMIDBITS_SHIFT) == 2) ? 16 : 8;
}

+#ifdef CONFIG_KVM_ARM_NESTED_HYP
+struct kvm_nested_s2_mmu *get_nested_mmu(struct kvm_vcpu *vcpu, u64 vttbr);
+struct kvm_s2_mmu *vcpu_get_active_s2_mmu(struct kvm_vcpu *vcpu);
+#else
+static inline struct kvm_nested_s2_mmu *get_nested_mmu(struct kvm_vcpu *vcpu,
+ u64 vttbr)
+{
+ return NULL;
+}
+static inline struct kvm_s2_mmu *vcpu_get_active_s2_mmu(struct kvm_vcpu *vcpu)
+{
+ return &vcpu->kvm->arch.mmu;
+}
+#endif
+
static inline u64 kvm_get_vttbr(struct kvm_s2_vmid *vmid,
struct kvm_s2_mmu *mmu)
{
@@ -334,5 +350,20 @@ static inline u64 kvm_get_vttbr(struct kvm_s2_vmid *vmid,
return baddr | vmid_field;
}

+static inline u64 get_vmid(u64 vttbr)
+{
+ return (vttbr & VTTBR_VMID_MASK(get_kvm_vmid_bits()))>>VTTBR_VMID_SHIFT;
+}
+
+static inline struct kvm_s2_vmid *vcpu_get_active_vmid(struct kvm_vcpu *vcpu)
+{
+ struct kvm_s2_mmu *mmu = vcpu_get_active_s2_mmu(vcpu);
+
+ if (unlikely(vcpu_mode_el2(vcpu)))
+ return &mmu->el2_vmid;
+ else
+ return &mmu->vmid;
+}
+
#endif /* __ASSEMBLY__ */
#endif /* __ARM64_KVM_MMU_H__ */
diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 8573faf..b0b1074 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -36,5 +36,6 @@ kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/arch_timer.o
kvm-$(CONFIG_KVM_ARM_PMU) += $(KVM)/arm/pmu.o

kvm-$(CONFIG_KVM_ARM_NESTED_HYP) += handle_exit_nested.o
+kvm-$(CONFIG_KVM_ARM_NESTED_HYP) += mmu-nested.o
kvm-$(CONFIG_KVM_ARM_NESTED_HYP) += emulate-nested.o
kvm-$(CONFIG_KVM_ARM_NESTED_HYP) += $(KVM)/arm/vgic/vgic-v2-nested.o
diff --git a/arch/arm64/kvm/context.c b/arch/arm64/kvm/context.c
index b2c0220..9ebc38f 100644
--- a/arch/arm64/kvm/context.c
+++ b/arch/arm64/kvm/context.c
@@ -91,7 +91,7 @@ static void create_shadow_el1_sysregs(struct kvm_vcpu *vcpu)

static void setup_s2_mmu(struct kvm_vcpu *vcpu)
{
- struct kvm_s2_mmu *mmu = &vcpu->kvm->arch.mmu;
+ struct kvm_s2_mmu *mmu = vcpu_get_active_s2_mmu(vcpu);
struct kvm_s2_vmid *vmid = vcpu_get_active_vmid(vcpu);

vcpu->arch.hw_vttbr = kvm_get_vttbr(vmid, mmu);
diff --git a/arch/arm64/kvm/mmu-nested.c b/arch/arm64/kvm/mmu-nested.c
new file mode 100644
index 0000000..d52078f
--- /dev/null
+++ b/arch/arm64/kvm/mmu-nested.c
@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2016 - Columbia University
+ * Author: Jintack Lim <jintack@cs.columbia.edu>
+ *
+ * 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 <linux/kvm_host.h>
+
+#include <asm/kvm_arm.h>
+#include <asm/kvm_emulate.h>
+#include <asm/kvm_mmu.h>
+#include <asm/kvm_nested.h>
+
+struct kvm_nested_s2_mmu *get_nested_mmu(struct kvm_vcpu *vcpu, u64 vttbr)
+{
+ struct kvm_nested_s2_mmu *mmu;
+ u64 target_vmid = get_vmid(vttbr);
+ struct list_head *nested_mmu_list = &vcpu->kvm->arch.nested_mmu_list;
+
+ list_for_each_entry_rcu(mmu, nested_mmu_list, list) {
+ u64 vmid = get_vmid(mmu->virtual_vttbr);
+
+ if (target_vmid == vmid)
+ return mmu;
+ }
+ return NULL;
+}
+
+struct kvm_s2_mmu *vcpu_get_active_s2_mmu(struct kvm_vcpu *vcpu)
+{
+ struct kvm_nested_s2_mmu *nested_mmu;
+
+ /* If we are NOT entering the nested VM, return mmu in kvm_arch */
+ if (vcpu_mode_el2(vcpu) || !vcpu_nested_stage2_enabled(vcpu))
+ return &vcpu->kvm->arch.mmu;
+
+ /* Otherwise, search for nested_mmu in the list */
+ nested_mmu = get_nested_mmu(vcpu, vcpu_el2_reg(vcpu, VTTBR_EL2));
+
+ /* When this function is called, nested_mmu should be in the list */
+ BUG_ON(!nested_mmu);
+
+ return &nested_mmu->mmu;
+}
--
1.9.1