When KVM runs in protected nVHE mode, make use of a stage 2 page-table
to give the hypervisor some control over the host memory accesses. At
the moment all memory aborts from the host will be instantly idmapped
RWX at stage 2 in a lazy fashion. Later patches will make use of that
infrastructure to implement access control restrictions to e.g. protect
guest memory from the host.
Signed-off-by: Quentin Perret <qperret@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_cpufeature.h | 2 +
arch/arm64/kernel/image-vars.h | 3 +
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 33 +++
arch/arm64/kvm/hyp/nvhe/Makefile | 2 +-
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 6 +
arch/arm64/kvm/hyp/nvhe/mem_protect.c | 191 ++++++++++++++++++
arch/arm64/kvm/hyp/nvhe/setup.c | 6 +
arch/arm64/kvm/hyp/nvhe/switch.c | 7 +-
arch/arm64/kvm/hyp/nvhe/tlb.c | 4 +-
9 files changed, 247 insertions(+), 7 deletions(-)
create mode 100644 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
create mode 100644 arch/arm64/kvm/hyp/nvhe/mem_protect.c
diff --git a/arch/arm64/include/asm/kvm_cpufeature.h b/arch/arm64/include/asm/kvm_cpufeature.h
index d34f85cba358..74043a149322 100644
--- a/arch/arm64/include/asm/kvm_cpufeature.h
+++ b/arch/arm64/include/asm/kvm_cpufeature.h
@@ -15,3 +15,5 @@
#endif
KVM_HYP_CPU_FTR_REG(SYS_CTR_EL0, arm64_ftr_reg_ctrel0)
+KVM_HYP_CPU_FTR_REG(SYS_ID_AA64MMFR0_EL1, arm64_ftr_reg_id_aa64mmfr0_el1)
+KVM_HYP_CPU_FTR_REG(SYS_ID_AA64MMFR1_EL1, arm64_ftr_reg_id_aa64mmfr1_el1)
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index f2d43e6cd86d..e2652278dd63 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -137,6 +137,9 @@ KVM_NVHE_ALIAS(__hyp_data_ro_after_init_end);
KVM_NVHE_ALIAS(__hyp_bss_start);
KVM_NVHE_ALIAS(__hyp_bss_end);
+/* pKVM static key */
+KVM_NVHE_ALIAS(kvm_protected_mode_initialized);
+
#endif /* CONFIG_KVM */
#endif /* __ARM64_KERNEL_IMAGE_VARS_H */
diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
new file mode 100644
index 000000000000..a22ef118a610
--- /dev/null
+++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020 Google LLC
+ * Author: Quentin Perret <qperret@xxxxxxxxxx>
+ */
+
+#ifndef __KVM_NVHE_MEM_PROTECT__
+#define __KVM_NVHE_MEM_PROTECT__
+#include <linux/kvm_host.h>
+#include <asm/kvm_hyp.h>
+#include <asm/kvm_pgtable.h>
+#include <asm/virt.h>
+#include <nvhe/spinlock.h>
+
+struct host_kvm {
+ struct kvm_arch arch;
+ struct kvm_pgtable pgt;
+ struct kvm_pgtable_mm_ops mm_ops;
+ hyp_spinlock_t lock;
+};
+extern struct host_kvm host_kvm;
+
+int kvm_host_prepare_stage2(void *mem_pgt_pool, void *dev_pgt_pool);
+void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt);
+
+static __always_inline void __load_host_stage2(void)
+{
+ if (static_branch_likely(&kvm_protected_mode_initialized))
+ __load_stage2(&host_kvm.arch.mmu, host_kvm.arch.vtcr);
+ else
+ write_sysreg(0, vttbr_el2);
+}
+#endif /* __KVM_NVHE_MEM_PROTECT__ */
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index d7381a503182..c3e2f98555c4 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -11,7 +11,7 @@ lib-objs := $(addprefix ../../../lib/, $(lib-objs))
obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o page_alloc.o \
- cache.o cpufeature.o setup.o mm.o
+ cache.o cpufeature.o setup.o mm.o mem_protect.o
obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o
obj-y += $(lib-objs)
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index a0bfe0d26da6..5d0cb17e03a1 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -13,6 +13,7 @@
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmu.h>
+#include <nvhe/mem_protect.h>
#include <nvhe/mm.h>
DEFINE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params);
@@ -234,6 +235,11 @@ void handle_trap(struct kvm_cpu_context *host_ctxt)
case ESR_ELx_EC_SMC64:
handle_host_smc(host_ctxt);
break;
+ case ESR_ELx_EC_IABT_LOW:
+ fallthrough;
+ case ESR_ELx_EC_DABT_LOW:
+ handle_host_mem_abort(host_ctxt);
+ break;
default:
hyp_panic();
}
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
new file mode 100644
index 000000000000..0cd3eb178f3b
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -0,0 +1,191 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 Google LLC
+ * Author: Quentin Perret <qperret@xxxxxxxxxx>
+ */
+
+#include <linux/kvm_host.h>
+#include <asm/kvm_cpufeature.h>
+#include <asm/kvm_emulate.h>
+#include <asm/kvm_hyp.h>
+#include <asm/kvm_mmu.h>
+#include <asm/kvm_pgtable.h>
+#include <asm/stage2_pgtable.h>
+
+#include <hyp/switch.h>
+
+#include <nvhe/gfp.h>
+#include <nvhe/memory.h>
+#include <nvhe/mem_protect.h>
+#include <nvhe/mm.h>
+
+extern unsigned long hyp_nr_cpus;
+struct host_kvm host_kvm;
+
+struct hyp_pool host_s2_mem;
+struct hyp_pool host_s2_dev;
+
+static void *host_s2_zalloc_pages_exact(size_t size)
+{
+ return hyp_alloc_pages(&host_s2_mem, HYP_GFP_ZERO, get_order(size));
+}
+
+static void *host_s2_zalloc_page(void *pool)
+{
+ return hyp_alloc_pages(pool, HYP_GFP_ZERO, 0);
+}
+
+static int prepare_s2_pools(void *mem_pgt_pool, void *dev_pgt_pool)
+{
+ unsigned long nr_pages;
+ int ret;
+
+ nr_pages = host_s2_mem_pgtable_size() >> PAGE_SHIFT;
+ ret = hyp_pool_init(&host_s2_mem, __hyp_pa(mem_pgt_pool), nr_pages, 0);
+ if (ret)
+ return ret;
+
+ nr_pages = host_s2_dev_pgtable_size() >> PAGE_SHIFT;
+ ret = hyp_pool_init(&host_s2_dev, __hyp_pa(dev_pgt_pool), nr_pages, 0);
+ if (ret)
+ return ret;
+
+ host_kvm.mm_ops.zalloc_pages_exact = host_s2_zalloc_pages_exact;
+ host_kvm.mm_ops.zalloc_page = host_s2_zalloc_page;
+ host_kvm.mm_ops.phys_to_virt = hyp_phys_to_virt;
+ host_kvm.mm_ops.virt_to_phys = hyp_virt_to_phys;
+ host_kvm.mm_ops.page_count = hyp_page_count;
+ host_kvm.mm_ops.get_page = hyp_get_page;
+ host_kvm.mm_ops.put_page = hyp_put_page;
+
+ return 0;
+}
+
+static void prepare_host_vtcr(void)
+{
+ u32 parange, phys_shift;
+ u64 mmfr0, mmfr1;
+
+ mmfr0 = arm64_ftr_reg_id_aa64mmfr0_el1.sys_val;
+ mmfr1 = arm64_ftr_reg_id_aa64mmfr1_el1.sys_val;
+
+ /* The host stage 2 is id-mapped, so use parange for T0SZ */
+ parange = kvm_get_parange(mmfr0);
+ phys_shift = id_aa64mmfr0_parange_to_phys_shift(parange);
+
+ host_kvm.arch.vtcr = kvm_get_vtcr(mmfr0, mmfr1, phys_shift);
+}
+
+int kvm_host_prepare_stage2(void *mem_pgt_pool, void *dev_pgt_pool)
+{
+ struct kvm_s2_mmu *mmu = &host_kvm.arch.mmu;
+ struct kvm_nvhe_init_params *params;
+ int ret, i;
+
+ prepare_host_vtcr();
+ hyp_spin_lock_init(&host_kvm.lock);
+
+ ret = prepare_s2_pools(mem_pgt_pool, dev_pgt_pool);
+ if (ret)
+ return ret;
+
+ ret = kvm_pgtable_stage2_init(&host_kvm.pgt, &host_kvm.arch,
+ &host_kvm.mm_ops);
+ if (ret)
+ return ret;
+
+ 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;
+
+ for (i = 0; i < hyp_nr_cpus; i++) {
+ params = per_cpu_ptr(&kvm_init_params, i);
+ params->vttbr = kvm_get_vttbr(mmu);
+ params->vtcr = host_kvm.arch.vtcr;
+ params->hcr_el2 |= HCR_VM;
+ __flush_dcache_area(params, sizeof(*params));
+ }
+
+ write_sysreg(this_cpu_ptr(&kvm_init_params)->hcr_el2, hcr_el2);
+ __load_stage2(&host_kvm.arch.mmu, host_kvm.arch.vtcr);
+
+ return 0;
+}
+
+static void host_stage2_unmap_dev_all(void)
+{
+ struct kvm_pgtable *pgt = &host_kvm.pgt;
+ struct hyp_memblock_region *reg;
+ u64 addr = 0;
+ int i;
+
+ /* Unmap all non-memory regions to recycle the pages */
+ for (i = 0; i < hyp_memblock_nr; i++, addr = reg->end) {
+ reg = &hyp_memory[i];
+ kvm_pgtable_stage2_unmap(pgt, addr, reg->start - addr);
+ }
+ kvm_pgtable_stage2_unmap(pgt, addr, ULONG_MAX);
+}
+
+static bool ipa_is_memory(u64 ipa)
+{
+ int cur, left = 0, right = hyp_memblock_nr;
+ struct hyp_memblock_region *reg;
+
+ /* The list of memblock regions is sorted, binary search it */
+ while (left < right) {
+ cur = (left + right) >> 1;
+ reg = &hyp_memory[cur];
+ if (ipa < reg->start)
+ right = cur;
+ else if (ipa >= reg->end)
+ left = cur + 1;
+ else
+ return true;
+ }
+
+ return false;
+}
+
+static int __host_stage2_map(u64 ipa, u64 size, enum kvm_pgtable_prot prot,
+ struct hyp_pool *p)
+{
+ return kvm_pgtable_stage2_map(&host_kvm.pgt, ipa, size, ipa, prot, p);
+}
+
+static int host_stage2_map(u64 ipa, u64 size, enum kvm_pgtable_prot prot)
+{
+ int ret, is_memory = ipa_is_memory(ipa);
+ struct hyp_pool *pool;
+
+ pool = is_memory ? &host_s2_mem : &host_s2_dev;
+
+ hyp_spin_lock(&host_kvm.lock);
+ ret = __host_stage2_map(ipa, size, prot, pool);
+ if (ret == -ENOMEM && !is_memory) {
+ host_stage2_unmap_dev_all();
+ ret = __host_stage2_map(ipa, size, prot, pool);
+ }
+ hyp_spin_unlock(&host_kvm.lock);
+
+ return ret;
+}
+
+void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
+{
+ enum kvm_pgtable_prot prot;
+ u64 far, hpfar, esr, ipa;
+ int ret;
+
+ esr = read_sysreg_el2(SYS_ESR);
+ if (!__get_fault_info(esr, &far, &hpfar))
+ hyp_panic();
+
+ prot = KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W | KVM_PGTABLE_PROT_X;
+ ipa = (hpfar & HPFAR_MASK) << 8;
+ ret = host_stage2_map(ipa, PAGE_SIZE, prot);
+ if (ret)
+ hyp_panic();
+}
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index b73e6b08cfba..3e079027e608 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -12,6 +12,7 @@
#include <nvhe/early_alloc.h>
#include <nvhe/gfp.h>
#include <nvhe/memory.h>
+#include <nvhe/mem_protect.h>
#include <nvhe/mm.h>
struct hyp_pool hpool;
@@ -161,6 +162,11 @@ void __noreturn __kvm_hyp_protect_finalise(void)
if (ret)
goto out;
+ /* Wrap the host with a stage 2 */
+ ret = kvm_host_prepare_stage2(host_s2_mem_pgt_base, host_s2_dev_pgt_base);
+ if (ret)
+ goto out;
+
hyp_pgtable_mm_ops.zalloc_page = hyp_zalloc_hyp_page;
hyp_pgtable_mm_ops.phys_to_virt = hyp_phys_to_virt;
hyp_pgtable_mm_ops.virt_to_phys = hyp_virt_to_phys;
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 979a76cdf9fb..31bc1a843bf8 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -28,6 +28,8 @@
#include <asm/processor.h>
#include <asm/thread_info.h>
+#include <nvhe/mem_protect.h>
+
/* Non-VHE specific context */
DEFINE_PER_CPU(struct kvm_host_data, kvm_host_data);
DEFINE_PER_CPU(struct kvm_cpu_context, kvm_hyp_ctxt);
@@ -102,11 +104,6 @@ static void __deactivate_traps(struct kvm_vcpu *vcpu)
write_sysreg(__kvm_hyp_host_vector, vbar_el2);
}
-static void __load_host_stage2(void)
-{
- write_sysreg(0, vttbr_el2);
-}
-
/* Save VGICv3 state on non-VHE systems */
static void __hyp_vgic_save_state(struct kvm_vcpu *vcpu)
{
diff --git a/arch/arm64/kvm/hyp/nvhe/tlb.c b/arch/arm64/kvm/hyp/nvhe/tlb.c
index fbde89a2c6e8..255a23a1b2db 100644
--- a/arch/arm64/kvm/hyp/nvhe/tlb.c
+++ b/arch/arm64/kvm/hyp/nvhe/tlb.c
@@ -8,6 +8,8 @@
#include <asm/kvm_mmu.h>
#include <asm/tlbflush.h>
+#include <nvhe/mem_protect.h>
+
struct tlb_inv_context {
u64 tcr;
};
@@ -43,7 +45,7 @@ static void __tlb_switch_to_guest(struct kvm_s2_mmu *mmu,
static void __tlb_switch_to_host(struct tlb_inv_context *cxt)
{
- write_sysreg(0, vttbr_el2);
+ __load_host_stage2();
if (cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT)) {
/* Ensure write of the host VMID */
--
2.29.2.299.gdc1121823c-goog
