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Merge branch kvm-arm64/pkvm/restrict-hypercalls into kvmarm-master/next

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* kvm-arm64/pkvm/restrict-hypercalls:
  : .
  : Restrict the use of some hypercalls as well as kexec once
  : the protected KVM mode has been initialised.
  : .
  KVM: arm64: Disable privileged hypercalls after pKVM finalisation
  KVM: arm64: Prevent re-finalisation of pKVM for a given CPU
  KVM: arm64: Propagate errors from __pkvm_prot_finalize hypercall
  KVM: arm64: Reject stub hypercalls after pKVM has been initialised
  arm64: Prevent kexec and hibernation if is_protected_kvm_enabled()
  KVM: arm64: Turn __KVM_HOST_SMCCC_FUNC_* into an enum (mostly)

Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier
2021-10-11 09:21:37 +01:00
parent 9e1ff307c7 057bed206f
commit 3864d17f17
6 changed files with 118 additions and 61 deletions
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47
arch/arm64/include/asm/kvm_asm.h
View File

@@ -44,31 +44,38 @@
#define KVM_HOST_SMCCC_FUNC(name) KVM_HOST_SMCCC_ID(__KVM_HOST_SMCCC_FUNC_##name)
#define __KVM_HOST_SMCCC_FUNC___kvm_hyp_init 0
#define __KVM_HOST_SMCCC_FUNC___kvm_vcpu_run 1
#define __KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context 2
#define __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid_ipa 3
#define __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid 4
#define __KVM_HOST_SMCCC_FUNC___kvm_flush_cpu_context 5
#define __KVM_HOST_SMCCC_FUNC___kvm_timer_set_cntvoff 6
#define __KVM_HOST_SMCCC_FUNC___kvm_enable_ssbs 7
#define __KVM_HOST_SMCCC_FUNC___vgic_v3_get_gic_config 8
#define __KVM_HOST_SMCCC_FUNC___vgic_v3_read_vmcr 9
#define __KVM_HOST_SMCCC_FUNC___vgic_v3_write_vmcr 10
#define __KVM_HOST_SMCCC_FUNC___vgic_v3_init_lrs 11
#define __KVM_HOST_SMCCC_FUNC___kvm_get_mdcr_el2 12
#define __KVM_HOST_SMCCC_FUNC___vgic_v3_save_aprs 13
#define __KVM_HOST_SMCCC_FUNC___vgic_v3_restore_aprs 14
#define __KVM_HOST_SMCCC_FUNC___pkvm_init 15
#define __KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp 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
#define __KVM_HOST_SMCCC_FUNC___kvm_adjust_pc 20
#ifndef __ASSEMBLY__
#include <linux/mm.h>
enum __kvm_host_smccc_func {
/* Hypercalls available only prior to pKVM finalisation */
/* __KVM_HOST_SMCCC_FUNC___kvm_hyp_init */
__KVM_HOST_SMCCC_FUNC___kvm_get_mdcr_el2 = __KVM_HOST_SMCCC_FUNC___kvm_hyp_init + 1,
__KVM_HOST_SMCCC_FUNC___pkvm_init,
__KVM_HOST_SMCCC_FUNC___pkvm_create_private_mapping,
__KVM_HOST_SMCCC_FUNC___pkvm_cpu_set_vector,
__KVM_HOST_SMCCC_FUNC___kvm_enable_ssbs,
__KVM_HOST_SMCCC_FUNC___vgic_v3_init_lrs,
__KVM_HOST_SMCCC_FUNC___vgic_v3_get_gic_config,
__KVM_HOST_SMCCC_FUNC___pkvm_prot_finalize,
/* Hypercalls available after pKVM finalisation */
__KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp,
__KVM_HOST_SMCCC_FUNC___kvm_adjust_pc,
__KVM_HOST_SMCCC_FUNC___kvm_vcpu_run,
__KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context,
__KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid_ipa,
__KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid,
__KVM_HOST_SMCCC_FUNC___kvm_flush_cpu_context,
__KVM_HOST_SMCCC_FUNC___kvm_timer_set_cntvoff,
__KVM_HOST_SMCCC_FUNC___vgic_v3_read_vmcr,
__KVM_HOST_SMCCC_FUNC___vgic_v3_write_vmcr,
__KVM_HOST_SMCCC_FUNC___vgic_v3_save_aprs,
__KVM_HOST_SMCCC_FUNC___vgic_v3_restore_aprs,
};
#define DECLARE_KVM_VHE_SYM(sym) extern char sym[]
#define DECLARE_KVM_NVHE_SYM(sym) extern char kvm_nvhe_sym(sym)[]

3
arch/arm64/kernel/smp.c
View File

@@ -1128,5 +1128,6 @@ bool cpus_are_stuck_in_kernel(void)
{
bool smp_spin_tables = (num_possible_cpus() > 1 && !have_cpu_die());
return !!cpus_stuck_in_kernel || smp_spin_tables;
return !!cpus_stuck_in_kernel || smp_spin_tables ||
is_protected_kvm_enabled();
}

63
arch/arm64/kvm/arm.c
View File

@@ -1579,25 +1579,33 @@ static void cpu_set_hyp_vector(void)
kvm_call_hyp_nvhe(__pkvm_cpu_set_vector, data->slot);
}
static void cpu_hyp_reinit(void)
static void cpu_hyp_init_context(void)
{
kvm_init_host_cpu_context(&this_cpu_ptr_hyp_sym(kvm_host_data)->host_ctxt);
cpu_hyp_reset();
if (!is_kernel_in_hyp_mode())
cpu_init_hyp_mode();
}
static void cpu_hyp_init_features(void)
{
cpu_set_hyp_vector();
kvm_arm_init_debug();
if (is_kernel_in_hyp_mode())
kvm_timer_init_vhe();
else
cpu_init_hyp_mode();
cpu_set_hyp_vector();
kvm_arm_init_debug();
if (vgic_present)
kvm_vgic_init_cpu_hardware();
}
static void cpu_hyp_reinit(void)
{
cpu_hyp_reset();
cpu_hyp_init_context();
cpu_hyp_init_features();
}
static void _kvm_arch_hardware_enable(void *discard)
{
if (!__this_cpu_read(kvm_arm_hardware_enabled)) {
@@ -1788,10 +1796,17 @@ static int do_pkvm_init(u32 hyp_va_bits)
int ret;
preempt_disable();
hyp_install_host_vector();
cpu_hyp_init_context();
ret = kvm_call_hyp_nvhe(__pkvm_init, hyp_mem_base, hyp_mem_size,
num_possible_cpus(), kern_hyp_va(per_cpu_base),
hyp_va_bits);
cpu_hyp_init_features();
/*
* The stub hypercalls are now disabled, so set our local flag to
* prevent a later re-init attempt in kvm_arch_hardware_enable().
*/
__this_cpu_write(kvm_arm_hardware_enabled, 1);
preempt_enable();
return ret;
@@ -1971,9 +1986,25 @@ static int init_hyp_mode(void)
return err;
}
static void _kvm_host_prot_finalize(void *discard)
static void _kvm_host_prot_finalize(void *arg)
{
WARN_ON(kvm_call_hyp_nvhe(__pkvm_prot_finalize));
int *err = arg;
if (WARN_ON(kvm_call_hyp_nvhe(__pkvm_prot_finalize)))
WRITE_ONCE(*err, -EINVAL);
}
static int pkvm_drop_host_privileges(void)
{
int ret = 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, &ret, 1);
return ret;
}
static int finalize_hyp_mode(void)
@@ -1987,15 +2018,7 @@ static int finalize_hyp_mode(void)
* None of other sections should ever be introspected.
*/
kmemleak_free_part(__hyp_bss_start, __hyp_bss_end - __hyp_bss_start);
/*
* 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;
return pkvm_drop_host_privileges();
}
struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr)

26
arch/arm64/kvm/hyp/nvhe/host.S
View File

@@ -110,17 +110,14 @@ SYM_FUNC_START(__hyp_do_panic)
b __host_enter_for_panic
SYM_FUNC_END(__hyp_do_panic)
.macro host_el1_sync_vect
.align 7
.L__vect_start\@:
stp x0, x1, [sp, #-16]!
mrs x0, esr_el2
lsr x0, x0, #ESR_ELx_EC_SHIFT
cmp x0, #ESR_ELx_EC_HVC64
b.ne __host_exit
SYM_FUNC_START(__host_hvc)
ldp x0, x1, [sp] // Don't fixup the stack yet
/* No stub for you, sonny Jim */
alternative_if ARM64_KVM_PROTECTED_MODE
b __host_exit
alternative_else_nop_endif
/* Check for a stub HVC call */
cmp x0, #HVC_STUB_HCALL_NR
b.hs __host_exit
@@ -137,6 +134,17 @@ SYM_FUNC_END(__hyp_do_panic)
ldr x5, =__kvm_handle_stub_hvc
hyp_pa x5, x6
br x5
SYM_FUNC_END(__host_hvc)
.macro host_el1_sync_vect
.align 7
.L__vect_start\@:
stp x0, x1, [sp, #-16]!
mrs x0, esr_el2
lsr x0, x0, #ESR_ELx_EC_SHIFT
cmp x0, #ESR_ELx_EC_HVC64
b.eq __host_hvc
b __host_exit
.L__vect_end\@:
.if ((.L__vect_end\@ - .L__vect_start\@) > 0x80)
.error "host_el1_sync_vect larger than vector entry"

37
arch/arm64/kvm/hyp/nvhe/hyp-main.c
View File

@@ -165,36 +165,51 @@ typedef void (*hcall_t)(struct kvm_cpu_context *);
#define HANDLE_FUNC(x) [__KVM_HOST_SMCCC_FUNC_##x] = (hcall_t)handle_##x
static const hcall_t host_hcall[] = {
HANDLE_FUNC(__kvm_vcpu_run),
/* ___kvm_hyp_init */
HANDLE_FUNC(__kvm_get_mdcr_el2),
HANDLE_FUNC(__pkvm_init),
HANDLE_FUNC(__pkvm_create_private_mapping),
HANDLE_FUNC(__pkvm_cpu_set_vector),
HANDLE_FUNC(__kvm_enable_ssbs),
HANDLE_FUNC(__vgic_v3_init_lrs),
HANDLE_FUNC(__vgic_v3_get_gic_config),
HANDLE_FUNC(__pkvm_prot_finalize),
HANDLE_FUNC(__pkvm_host_share_hyp),
HANDLE_FUNC(__kvm_adjust_pc),
HANDLE_FUNC(__kvm_vcpu_run),
HANDLE_FUNC(__kvm_flush_vm_context),
HANDLE_FUNC(__kvm_tlb_flush_vmid_ipa),
HANDLE_FUNC(__kvm_tlb_flush_vmid),
HANDLE_FUNC(__kvm_flush_cpu_context),
HANDLE_FUNC(__kvm_timer_set_cntvoff),
HANDLE_FUNC(__kvm_enable_ssbs),
HANDLE_FUNC(__vgic_v3_get_gic_config),
HANDLE_FUNC(__vgic_v3_read_vmcr),
HANDLE_FUNC(__vgic_v3_write_vmcr),
HANDLE_FUNC(__vgic_v3_init_lrs),
HANDLE_FUNC(__kvm_get_mdcr_el2),
HANDLE_FUNC(__vgic_v3_save_aprs),
HANDLE_FUNC(__vgic_v3_restore_aprs),
HANDLE_FUNC(__pkvm_init),
HANDLE_FUNC(__pkvm_cpu_set_vector),
HANDLE_FUNC(__pkvm_host_share_hyp),
HANDLE_FUNC(__pkvm_create_private_mapping),
HANDLE_FUNC(__pkvm_prot_finalize),
};
static void handle_host_hcall(struct kvm_cpu_context *host_ctxt)
{
DECLARE_REG(unsigned long, id, host_ctxt, 0);
unsigned long hcall_min = 0;
hcall_t hfn;
/*
* If pKVM has been initialised then reject any calls to the
* early "privileged" hypercalls. Note that we cannot reject
* calls to __pkvm_prot_finalize for two reasons: (1) The static
* key used to determine initialisation must be toggled prior to
* finalisation and (2) finalisation is performed on a per-CPU
* basis. This is all fine, however, since __pkvm_prot_finalize
* returns -EPERM after the first call for a given CPU.
*/
if (static_branch_unlikely(&kvm_protected_mode_initialized))
hcall_min = __KVM_HOST_SMCCC_FUNC___pkvm_prot_finalize;
id -= KVM_HOST_SMCCC_ID(0);
if (unlikely(id >= ARRAY_SIZE(host_hcall)))
if (unlikely(id < hcall_min || id >= ARRAY_SIZE(host_hcall)))
goto inval;
hfn = host_hcall[id];

3
arch/arm64/kvm/hyp/nvhe/mem_protect.c
View File

@@ -123,6 +123,9 @@ 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);
if (params->hcr_el2 & HCR_VM)
return -EPERM;
params->vttbr = kvm_get_vttbr(mmu);
params->vtcr = host_kvm.arch.vtcr;
params->hcr_el2 |= HCR_VM;