Commit 1025c8c0 authored by Quentin Perret's avatar Quentin Perret Committed by Marc Zyngier

KVM: arm64: Wrap the host with a stage 2

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. The
host stage 2 is created lazily using large block mappings if possible,
and will default to page mappings in absence of a better solution.

>From this point on, memory accesses from the host to protected memory
regions (e.g. not 'owned' by the host) are fatal and lead to hyp_panic().
Acked-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarQuentin Perret <qperret@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-36-qperret@google.com
parent def1aaf9
......@@ -61,6 +61,7 @@
#define __KVM_HOST_SMCCC_FUNC___pkvm_create_mappings 16
#define __KVM_HOST_SMCCC_FUNC___pkvm_create_private_mapping 17
#define __KVM_HOST_SMCCC_FUNC___pkvm_cpu_set_vector 18
#define __KVM_HOST_SMCCC_FUNC___pkvm_prot_finalize 19
#ifndef __ASSEMBLY__
......
......@@ -131,6 +131,9 @@ KVM_NVHE_ALIAS(__hyp_bss_end);
KVM_NVHE_ALIAS(__hyp_rodata_start);
KVM_NVHE_ALIAS(__hyp_rodata_end);
/* pKVM static key */
KVM_NVHE_ALIAS(kvm_protected_mode_initialized);
#endif /* CONFIG_KVM */
#endif /* __ARM64_KERNEL_IMAGE_VARS_H */
......@@ -1894,12 +1894,22 @@ static int init_hyp_mode(void)
return err;
}
void _kvm_host_prot_finalize(void *discard)
{
WARN_ON(kvm_call_hyp_nvhe(__pkvm_prot_finalize));
}
static int finalize_hyp_mode(void)
{
if (!is_protected_kvm_enabled())
return 0;
/*
* Flip the static key upfront as that may no longer be possible
* once the host stage 2 is installed.
*/
static_branch_enable(&kvm_protected_mode_initialized);
on_each_cpu(_kvm_host_prot_finalize, NULL, 1);
return 0;
}
......
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2020 Google LLC
* Author: Quentin Perret <qperret@google.com>
*/
#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 __pkvm_prot_finalize(void);
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__ */
......@@ -14,7 +14,7 @@ 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 setup.o mm.o
cache.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)
......
......@@ -119,6 +119,7 @@ alternative_else_nop_endif
/* Invalidate the stale TLBs from Bootloader */
tlbi alle2
tlbi vmalls12e1
dsb sy
/*
......
......@@ -13,6 +13,7 @@
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmu.h>
#include <nvhe/mem_protect.h>
#include <nvhe/mm.h>
#include <nvhe/trap_handler.h>
......@@ -151,6 +152,10 @@ static void handle___pkvm_create_private_mapping(struct kvm_cpu_context *host_ct
cpu_reg(host_ctxt, 1) = __pkvm_create_private_mapping(phys, size, prot);
}
static void handle___pkvm_prot_finalize(struct kvm_cpu_context *host_ctxt)
{
cpu_reg(host_ctxt, 1) = __pkvm_prot_finalize();
}
typedef void (*hcall_t)(struct kvm_cpu_context *);
#define HANDLE_FUNC(x) [__KVM_HOST_SMCCC_FUNC_##x] = (hcall_t)handle_##x
......@@ -174,6 +179,7 @@ static const hcall_t host_hcall[] = {
HANDLE_FUNC(__pkvm_cpu_set_vector),
HANDLE_FUNC(__pkvm_create_mappings),
HANDLE_FUNC(__pkvm_create_private_mapping),
HANDLE_FUNC(__pkvm_prot_finalize),
};
static void handle_host_hcall(struct kvm_cpu_context *host_ctxt)
......@@ -231,6 +237,10 @@ void handle_trap(struct kvm_cpu_context *host_ctxt)
isb();
sve_cond_update_zcr_vq(ZCR_ELx_LEN_MASK, SYS_ZCR_EL2);
break;
case ESR_ELx_EC_IABT_LOW:
case ESR_ELx_EC_DABT_LOW:
handle_host_mem_abort(host_ctxt);
break;
default:
hyp_panic();
}
......
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2020 Google LLC
* Author: Quentin Perret <qperret@google.com>
*/
#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>
#define KVM_HOST_S2_FLAGS (KVM_PGTABLE_S2_NOFWB | KVM_PGTABLE_S2_IDMAP)
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, get_order(size));
}
static void *host_s2_zalloc_page(void *pool)
{
return hyp_alloc_pages(pool, 0);
}
static int prepare_s2_pools(void *mem_pgt_pool, void *dev_pgt_pool)
{
unsigned long nr_pages, pfn;
int ret;
pfn = hyp_virt_to_pfn(mem_pgt_pool);
nr_pages = host_s2_mem_pgtable_pages();
ret = hyp_pool_init(&host_s2_mem, pfn, nr_pages, 0);
if (ret)
return ret;
pfn = hyp_virt_to_pfn(dev_pgt_pool);
nr_pages = host_s2_dev_pgtable_pages();
ret = hyp_pool_init(&host_s2_dev, pfn, nr_pages, 0);
if (ret)
return ret;
host_kvm.mm_ops = (struct kvm_pgtable_mm_ops) {
.zalloc_pages_exact = host_s2_zalloc_pages_exact,
.zalloc_page = host_s2_zalloc_page,
.phys_to_virt = hyp_phys_to_virt,
.virt_to_phys = hyp_virt_to_phys,
.page_count = hyp_page_count,
.get_page = hyp_get_page,
.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;
int ret;
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_flags(&host_kvm.pgt, &host_kvm.arch,
&host_kvm.mm_ops, KVM_HOST_S2_FLAGS);
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;
return 0;
}
int __pkvm_prot_finalize(void)
{
struct kvm_s2_mmu *mmu = &host_kvm.arch.mmu;
struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params);
params->vttbr = kvm_get_vttbr(mmu);
params->vtcr = host_kvm.arch.vtcr;
params->hcr_el2 |= HCR_VM;
kvm_flush_dcache_to_poc(params, sizeof(*params));
write_sysreg(params->hcr_el2, hcr_el2);
__load_stage2(&host_kvm.arch.mmu, host_kvm.arch.vtcr);
/*
* Make sure to have an ISB before the TLB maintenance below but only
* when __load_stage2() doesn't include one already.
*/
asm(ALTERNATIVE("isb", "nop", ARM64_WORKAROUND_SPECULATIVE_AT));
/* Invalidate stale HCR bits that may be cached in TLBs */
__tlbi(vmalls12e1);
dsb(nsh);
isb();
return 0;
}
static int host_stage2_unmap_dev_all(void)
{
struct kvm_pgtable *pgt = &host_kvm.pgt;
struct memblock_region *reg;
u64 addr = 0;
int i, ret;
/* Unmap all non-memory regions to recycle the pages */
for (i = 0; i < hyp_memblock_nr; i++, addr = reg->base + reg->size) {
reg = &hyp_memory[i];
ret = kvm_pgtable_stage2_unmap(pgt, addr, reg->base - addr);
if (ret)
return ret;
}
return kvm_pgtable_stage2_unmap(pgt, addr, BIT(pgt->ia_bits) - addr);
}
static bool find_mem_range(phys_addr_t addr, struct kvm_mem_range *range)
{
int cur, left = 0, right = hyp_memblock_nr;
struct memblock_region *reg;
phys_addr_t end;
range->start = 0;
range->end = ULONG_MAX;
/* The list of memblock regions is sorted, binary search it */
while (left < right) {
cur = (left + right) >> 1;
reg = &hyp_memory[cur];
end = reg->base + reg->size;
if (addr < reg->base) {
right = cur;
range->end = reg->base;
} else if (addr >= end) {
left = cur + 1;
range->start = end;
} else {
range->start = reg->base;
range->end = end;
return true;
}
}
return false;
}
static inline int __host_stage2_idmap(u64 start, u64 end,
enum kvm_pgtable_prot prot,
struct hyp_pool *pool)
{
return kvm_pgtable_stage2_map(&host_kvm.pgt, start, end - start, start,
prot, pool);
}
static int host_stage2_idmap(u64 addr)
{
enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W;
struct kvm_mem_range range;
bool is_memory = find_mem_range(addr, &range);
struct hyp_pool *pool = is_memory ? &host_s2_mem : &host_s2_dev;
int ret;
if (is_memory)
prot |= KVM_PGTABLE_PROT_X;
hyp_spin_lock(&host_kvm.lock);
ret = kvm_pgtable_stage2_find_range(&host_kvm.pgt, addr, prot, &range);
if (ret)
goto unlock;
ret = __host_stage2_idmap(range.start, range.end, prot, pool);
if (is_memory || ret != -ENOMEM)
goto unlock;
/*
* host_s2_mem has been provided with enough pages to cover all of
* memory with page granularity, so we should never hit the ENOMEM case.
* However, it is difficult to know how much of the MMIO range we will
* need to cover upfront, so we may need to 'recycle' the pages if we
* run out.
*/
ret = host_stage2_unmap_dev_all();
if (ret)
goto unlock;
ret = __host_stage2_idmap(range.start, range.end, prot, pool);
unlock:
hyp_spin_unlock(&host_kvm.lock);
return ret;
}
void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
{
struct kvm_vcpu_fault_info fault;
u64 esr, addr;
int ret = 0;
esr = read_sysreg_el2(SYS_ESR);
if (!__get_fault_info(esr, &fault))
hyp_panic();
addr = (fault.hpfar_el2 & HPFAR_MASK) << 8;
ret = host_stage2_idmap(addr);
if (ret && ret != -EAGAIN)
hyp_panic();
}
......@@ -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>
#include <nvhe/trap_handler.h>
......@@ -157,6 +158,10 @@ void __noreturn __pkvm_init_finalise(void)
if (ret)
goto out;
ret = kvm_host_prepare_stage2(host_s2_mem_pgt_base, host_s2_dev_pgt_base);
if (ret)
goto out;
pkvm_pgtable_mm_ops = (struct kvm_pgtable_mm_ops) {
.zalloc_page = hyp_zalloc_hyp_page,
.phys_to_virt = hyp_phys_to_virt,
......
......@@ -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);
......@@ -107,11 +109,6 @@ 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)
{
......
......@@ -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 */
......
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