* [PATCH v2 1/5] arm64: Prevent kexec and hibernation if is_protected_kvm_enabled()
2021-10-05 11:37 [PATCH v2 0/5] KVM: arm64: Restrict host hypercalls when pKVM is enabled Will Deacon
@ 2021-10-05 11:37 ` Will Deacon
2021-10-05 11:37 ` [PATCH v2 2/5] KVM: arm64: Reject stub hypercalls after pKVM has been initialised Will Deacon
` (3 subsequent siblings)
4 siblings, 0 replies; 9+ messages in thread
From: Will Deacon @ 2021-10-05 11:37 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Will Deacon, Marc Zyngier, Quentin Perret, Catalin Marinas,
Alexandru Elisei, Suzuki K Poulose, Mark Rutland, kvmarm
When pKVM is enabled, the hypervisor code at EL2 and its data structures
are inaccessible to the host kernel and cannot be torn down or replaced
as this would defeat the integrity properies which pKVM aims to provide.
Furthermore, the ABI between the host and EL2 is flexible and private to
whatever the current implementation of KVM requires and so booting a new
kernel with an old EL2 component is very likely to end in disaster.
In preparation for uninstalling the hyp stub calls which are relied upon
to reset EL2, disable kexec and hibernation in the host when protected
KVM is enabled.
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/kernel/smp.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 6f6ff072acbd..44369b99a57e 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -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();
}
--
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^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH v2 2/5] KVM: arm64: Reject stub hypercalls after pKVM has been initialised
2021-10-05 11:37 [PATCH v2 0/5] KVM: arm64: Restrict host hypercalls when pKVM is enabled Will Deacon
2021-10-05 11:37 ` [PATCH v2 1/5] arm64: Prevent kexec and hibernation if is_protected_kvm_enabled() Will Deacon
@ 2021-10-05 11:37 ` Will Deacon
2021-10-05 11:37 ` [PATCH v2 3/5] KVM: arm64: Propagate errors from __pkvm_prot_finalize hypercall Will Deacon
` (2 subsequent siblings)
4 siblings, 0 replies; 9+ messages in thread
From: Will Deacon @ 2021-10-05 11:37 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Will Deacon, Marc Zyngier, Quentin Perret, Catalin Marinas,
Alexandru Elisei, Suzuki K Poulose, Mark Rutland, kvmarm
The stub hypercalls provide mechanisms to reset and replace the EL2 code,
so uninstall them once pKVM has been initialised in order to ensure the
integrity of the hypervisor code.
To ensure pKVM initialisation remains functional, split cpu_hyp_reinit()
into two helper functions to separate usage of the stub from usage of
pkvm hypercalls either side of __pkvm_init on the boot CPU.
Cc: Marc Zyngier <maz@kernel.org>
Reviewed-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/kvm/arm.c | 31 +++++++++++++++++++++++--------
arch/arm64/kvm/hyp/nvhe/host.S | 26 +++++++++++++++++---------
2 files changed, 40 insertions(+), 17 deletions(-)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index fe102cd2e518..9506cf88fa0e 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -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())
- kvm_timer_init_vhe();
- else
+ 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();
+
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;
diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
index 4b652ffb591d..0c6116d34e18 100644
--- a/arch/arm64/kvm/hyp/nvhe/host.S
+++ b/arch/arm64/kvm/hyp/nvhe/host.S
@@ -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"
--
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^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH v2 3/5] KVM: arm64: Propagate errors from __pkvm_prot_finalize hypercall
2021-10-05 11:37 [PATCH v2 0/5] KVM: arm64: Restrict host hypercalls when pKVM is enabled Will Deacon
2021-10-05 11:37 ` [PATCH v2 1/5] arm64: Prevent kexec and hibernation if is_protected_kvm_enabled() Will Deacon
2021-10-05 11:37 ` [PATCH v2 2/5] KVM: arm64: Reject stub hypercalls after pKVM has been initialised Will Deacon
@ 2021-10-05 11:37 ` Will Deacon
2021-10-05 11:37 ` [PATCH v2 4/5] KVM: arm64: Prevent re-finalisation of pKVM for a given CPU Will Deacon
2021-10-05 11:37 ` [PATCH v2 5/5] KVM: arm64: Disable privileged hypercalls after pKVM finalisation Will Deacon
4 siblings, 0 replies; 9+ messages in thread
From: Will Deacon @ 2021-10-05 11:37 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Will Deacon, Marc Zyngier, Quentin Perret, Catalin Marinas,
Alexandru Elisei, Suzuki K Poulose, Mark Rutland, kvmarm
If the __pkvm_prot_finalize hypercall returns an error, we WARN but fail
to propagate the failure code back to kvm_arch_init().
Pass a pointer to a zero-initialised return variable so that failure
to finalise the pKVM protections on a host CPU can be reported back to
KVM.
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/kvm/arm.c | 30 +++++++++++++++++++-----------
1 file changed, 19 insertions(+), 11 deletions(-)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 9506cf88fa0e..13bbf35896cd 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1986,9 +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)
@@ -2002,15 +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)
--
2.33.0.800.g4c38ced690-goog
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^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH v2 4/5] KVM: arm64: Prevent re-finalisation of pKVM for a given CPU
2021-10-05 11:37 [PATCH v2 0/5] KVM: arm64: Restrict host hypercalls when pKVM is enabled Will Deacon
` (2 preceding siblings ...)
2021-10-05 11:37 ` [PATCH v2 3/5] KVM: arm64: Propagate errors from __pkvm_prot_finalize hypercall Will Deacon
@ 2021-10-05 11:37 ` Will Deacon
2021-10-05 11:37 ` [PATCH v2 5/5] KVM: arm64: Disable privileged hypercalls after pKVM finalisation Will Deacon
4 siblings, 0 replies; 9+ messages in thread
From: Will Deacon @ 2021-10-05 11:37 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Will Deacon, Marc Zyngier, Quentin Perret, Catalin Marinas,
Alexandru Elisei, Suzuki K Poulose, Mark Rutland, kvmarm
__pkvm_prot_finalize() completes the deprivilege of the host when pKVM
is in use by installing a stage-2 translation table for the calling CPU.
Issuing the hypercall multiple times for a given CPU makes little sense,
but in such a case just return early with -EPERM rather than go through
the whole page-table dance again.
Cc: Marc Zyngier <maz@kernel.org>
Reviewed-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/kvm/hyp/nvhe/mem_protect.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index bacd493a4eac..cafe17e5fa8f 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -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;
--
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^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH v2 5/5] KVM: arm64: Disable privileged hypercalls after pKVM finalisation
2021-10-05 11:37 [PATCH v2 0/5] KVM: arm64: Restrict host hypercalls when pKVM is enabled Will Deacon
` (3 preceding siblings ...)
2021-10-05 11:37 ` [PATCH v2 4/5] KVM: arm64: Prevent re-finalisation of pKVM for a given CPU Will Deacon
@ 2021-10-05 11:37 ` Will Deacon
2021-10-07 12:56 ` Marc Zyngier
4 siblings, 1 reply; 9+ messages in thread
From: Will Deacon @ 2021-10-05 11:37 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Will Deacon, Marc Zyngier, Quentin Perret, Catalin Marinas,
Alexandru Elisei, Suzuki K Poulose, Mark Rutland, kvmarm
After pKVM has been 'finalised' using the __pkvm_prot_finalize hypercall,
the calling CPU will have a Stage-2 translation enabled to prevent access
to memory pages owned by EL2.
Although this forms a significant part of the process to deprivilege the
host kernel, we also need to ensure that the hypercall interface is
reduced so that the EL2 code cannot, for example, be re-initialised using
a new set of vectors.
Re-order the hypercalls so that only a suffix remains available after
finalisation of pKVM.
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/include/asm/kvm_asm.h | 43 ++++++++++++++++--------------
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 37 +++++++++++++++++--------
2 files changed, 49 insertions(+), 31 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index e86045ac43ba..68630fd382c5 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -43,27 +43,30 @@
#define KVM_HOST_SMCCC_FUNC(name) KVM_HOST_SMCCC_ID(__KVM_HOST_SMCCC_FUNC_##name)
+/* Hypercalls available only prior to pKVM finalisation */
#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
+#define __KVM_HOST_SMCCC_FUNC___kvm_get_mdcr_el2 1
+#define __KVM_HOST_SMCCC_FUNC___pkvm_init 2
+#define __KVM_HOST_SMCCC_FUNC___pkvm_create_private_mapping 3
+#define __KVM_HOST_SMCCC_FUNC___pkvm_cpu_set_vector 4
+#define __KVM_HOST_SMCCC_FUNC___kvm_enable_ssbs 5
+#define __KVM_HOST_SMCCC_FUNC___vgic_v3_init_lrs 6
+#define __KVM_HOST_SMCCC_FUNC___vgic_v3_get_gic_config 7
+#define __KVM_HOST_SMCCC_FUNC___pkvm_prot_finalize 8
+
+/* Hypercalls available after pKVM finalisation */
+#define __KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp 9
+#define __KVM_HOST_SMCCC_FUNC___kvm_adjust_pc 10
+#define __KVM_HOST_SMCCC_FUNC___kvm_vcpu_run 11
+#define __KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context 12
+#define __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid_ipa 13
+#define __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid 14
+#define __KVM_HOST_SMCCC_FUNC___kvm_flush_cpu_context 15
+#define __KVM_HOST_SMCCC_FUNC___kvm_timer_set_cntvoff 16
+#define __KVM_HOST_SMCCC_FUNC___vgic_v3_read_vmcr 17
+#define __KVM_HOST_SMCCC_FUNC___vgic_v3_write_vmcr 18
+#define __KVM_HOST_SMCCC_FUNC___vgic_v3_save_aprs 19
+#define __KVM_HOST_SMCCC_FUNC___vgic_v3_restore_aprs 20
#ifndef __ASSEMBLY__
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 2da6aa8da868..8566805ef62c 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -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];
--
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^ permalink raw reply related [flat|nested] 9+ messages in thread* Re: [PATCH v2 5/5] KVM: arm64: Disable privileged hypercalls after pKVM finalisation
2021-10-05 11:37 ` [PATCH v2 5/5] KVM: arm64: Disable privileged hypercalls after pKVM finalisation Will Deacon
@ 2021-10-07 12:56 ` Marc Zyngier
2021-10-08 7:27 ` Will Deacon
0 siblings, 1 reply; 9+ messages in thread
From: Marc Zyngier @ 2021-10-07 12:56 UTC (permalink / raw)
To: Will Deacon
Cc: linux-arm-kernel, Quentin Perret, Catalin Marinas,
Alexandru Elisei, Suzuki K Poulose, Mark Rutland, kvmarm
On Tue, 05 Oct 2021 12:37:21 +0100,
Will Deacon <will@kernel.org> wrote:
>
> After pKVM has been 'finalised' using the __pkvm_prot_finalize hypercall,
> the calling CPU will have a Stage-2 translation enabled to prevent access
> to memory pages owned by EL2.
>
> Although this forms a significant part of the process to deprivilege the
> host kernel, we also need to ensure that the hypercall interface is
> reduced so that the EL2 code cannot, for example, be re-initialised using
> a new set of vectors.
>
> Re-order the hypercalls so that only a suffix remains available after
> finalisation of pKVM.
>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Quentin Perret <qperret@google.com>
> Signed-off-by: Will Deacon <will@kernel.org>
> ---
> arch/arm64/include/asm/kvm_asm.h | 43 ++++++++++++++++--------------
> arch/arm64/kvm/hyp/nvhe/hyp-main.c | 37 +++++++++++++++++--------
> 2 files changed, 49 insertions(+), 31 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
> index e86045ac43ba..68630fd382c5 100644
> --- a/arch/arm64/include/asm/kvm_asm.h
> +++ b/arch/arm64/include/asm/kvm_asm.h
> @@ -43,27 +43,30 @@
>
> #define KVM_HOST_SMCCC_FUNC(name) KVM_HOST_SMCCC_ID(__KVM_HOST_SMCCC_FUNC_##name)
>
> +/* Hypercalls available only prior to pKVM finalisation */
> #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
> +#define __KVM_HOST_SMCCC_FUNC___kvm_get_mdcr_el2 1
> +#define __KVM_HOST_SMCCC_FUNC___pkvm_init 2
> +#define __KVM_HOST_SMCCC_FUNC___pkvm_create_private_mapping 3
> +#define __KVM_HOST_SMCCC_FUNC___pkvm_cpu_set_vector 4
> +#define __KVM_HOST_SMCCC_FUNC___kvm_enable_ssbs 5
> +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_init_lrs 6
> +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_get_gic_config 7
> +#define __KVM_HOST_SMCCC_FUNC___pkvm_prot_finalize 8
> +
> +/* Hypercalls available after pKVM finalisation */
> +#define __KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp 9
> +#define __KVM_HOST_SMCCC_FUNC___kvm_adjust_pc 10
> +#define __KVM_HOST_SMCCC_FUNC___kvm_vcpu_run 11
> +#define __KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context 12
> +#define __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid_ipa 13
> +#define __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid 14
> +#define __KVM_HOST_SMCCC_FUNC___kvm_flush_cpu_context 15
> +#define __KVM_HOST_SMCCC_FUNC___kvm_timer_set_cntvoff 16
> +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_read_vmcr 17
> +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_write_vmcr 18
> +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_save_aprs 19
> +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_restore_aprs 20
This is no helping with the above, but can we *please* try to get rid
of this #define insanity before moving things around? I came up with
the following, which seems to build.
Thoughts?
M.
From 8a50c98489220d2ebaf02d4ffdbef3cf0d6634ee Mon Sep 17 00:00:00 2001
From: Marc Zyngier <maz@kernel.org>
Date: Thu, 7 Oct 2021 13:18:29 +0100
Subject: [PATCH] KVM: arm64: Turn __KVM_HOST_SMCCC_FUNC_* into an enum
(mostly)
__KVM_HOST_SMCCC_FUNC_* is a royal pain, as there is a fair amount
of churn around these #defines, and we avoid making it an enum
only for the sake of the early init, low level code that requires
__KVM_HOST_SMCCC_FUNC___kvm_hyp_init to be usable from assembly.
Let's be brave and turn everything but this symbol into an enum,
using a bit of arithmetic to avoid any overlap.
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/include/asm/kvm_asm.h | 44 +++++++++++++++++---------------
1 file changed, 24 insertions(+), 20 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index e86045ac43ba..43b5e213ae43 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -44,31 +44,35 @@
#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 {
+ /* __KVM_HOST_SMCCC_FUNC___kvm_hyp_init */
+ __KVM_HOST_SMCCC_FUNC___kvm_vcpu_run = __KVM_HOST_SMCCC_FUNC___kvm_hyp_init + 1,
+ __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___kvm_enable_ssbs,
+ __KVM_HOST_SMCCC_FUNC___vgic_v3_get_gic_config,
+ __KVM_HOST_SMCCC_FUNC___vgic_v3_read_vmcr,
+ __KVM_HOST_SMCCC_FUNC___vgic_v3_write_vmcr,
+ __KVM_HOST_SMCCC_FUNC___vgic_v3_init_lrs,
+ __KVM_HOST_SMCCC_FUNC___kvm_get_mdcr_el2,
+ __KVM_HOST_SMCCC_FUNC___vgic_v3_save_aprs,
+ __KVM_HOST_SMCCC_FUNC___vgic_v3_restore_aprs,
+ __KVM_HOST_SMCCC_FUNC___pkvm_init,
+ __KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp,
+ __KVM_HOST_SMCCC_FUNC___pkvm_create_private_mapping,
+ __KVM_HOST_SMCCC_FUNC___pkvm_cpu_set_vector,
+ __KVM_HOST_SMCCC_FUNC___pkvm_prot_finalize,
+ __KVM_HOST_SMCCC_FUNC___kvm_adjust_pc,
+};
+
#define DECLARE_KVM_VHE_SYM(sym) extern char sym[]
#define DECLARE_KVM_NVHE_SYM(sym) extern char kvm_nvhe_sym(sym)[]
--
2.30.2
--
Without deviation from the norm, progress is not possible.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 9+ messages in thread* Re: [PATCH v2 5/5] KVM: arm64: Disable privileged hypercalls after pKVM finalisation
2021-10-07 12:56 ` Marc Zyngier
@ 2021-10-08 7:27 ` Will Deacon
2021-10-08 7:31 ` Marc Zyngier
0 siblings, 1 reply; 9+ messages in thread
From: Will Deacon @ 2021-10-08 7:27 UTC (permalink / raw)
To: Marc Zyngier
Cc: linux-arm-kernel, Quentin Perret, Catalin Marinas,
Alexandru Elisei, Suzuki K Poulose, Mark Rutland, kvmarm
On Thu, Oct 07, 2021 at 01:56:47PM +0100, Marc Zyngier wrote:
> On Tue, 05 Oct 2021 12:37:21 +0100,
> Will Deacon <will@kernel.org> wrote:
> >
> > After pKVM has been 'finalised' using the __pkvm_prot_finalize hypercall,
> > the calling CPU will have a Stage-2 translation enabled to prevent access
> > to memory pages owned by EL2.
> >
> > Although this forms a significant part of the process to deprivilege the
> > host kernel, we also need to ensure that the hypercall interface is
> > reduced so that the EL2 code cannot, for example, be re-initialised using
> > a new set of vectors.
> >
> > Re-order the hypercalls so that only a suffix remains available after
> > finalisation of pKVM.
> >
> > Cc: Marc Zyngier <maz@kernel.org>
> > Cc: Quentin Perret <qperret@google.com>
> > Signed-off-by: Will Deacon <will@kernel.org>
> > ---
> > arch/arm64/include/asm/kvm_asm.h | 43 ++++++++++++++++--------------
> > arch/arm64/kvm/hyp/nvhe/hyp-main.c | 37 +++++++++++++++++--------
> > 2 files changed, 49 insertions(+), 31 deletions(-)
> >
> > diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
> > index e86045ac43ba..68630fd382c5 100644
> > --- a/arch/arm64/include/asm/kvm_asm.h
> > +++ b/arch/arm64/include/asm/kvm_asm.h
> > @@ -43,27 +43,30 @@
> >
> > #define KVM_HOST_SMCCC_FUNC(name) KVM_HOST_SMCCC_ID(__KVM_HOST_SMCCC_FUNC_##name)
> >
> > +/* Hypercalls available only prior to pKVM finalisation */
> > #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
> > +#define __KVM_HOST_SMCCC_FUNC___kvm_get_mdcr_el2 1
> > +#define __KVM_HOST_SMCCC_FUNC___pkvm_init 2
> > +#define __KVM_HOST_SMCCC_FUNC___pkvm_create_private_mapping 3
> > +#define __KVM_HOST_SMCCC_FUNC___pkvm_cpu_set_vector 4
> > +#define __KVM_HOST_SMCCC_FUNC___kvm_enable_ssbs 5
> > +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_init_lrs 6
> > +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_get_gic_config 7
> > +#define __KVM_HOST_SMCCC_FUNC___pkvm_prot_finalize 8
> > +
> > +/* Hypercalls available after pKVM finalisation */
> > +#define __KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp 9
> > +#define __KVM_HOST_SMCCC_FUNC___kvm_adjust_pc 10
> > +#define __KVM_HOST_SMCCC_FUNC___kvm_vcpu_run 11
> > +#define __KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context 12
> > +#define __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid_ipa 13
> > +#define __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid 14
> > +#define __KVM_HOST_SMCCC_FUNC___kvm_flush_cpu_context 15
> > +#define __KVM_HOST_SMCCC_FUNC___kvm_timer_set_cntvoff 16
> > +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_read_vmcr 17
> > +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_write_vmcr 18
> > +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_save_aprs 19
> > +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_restore_aprs 20
>
> This is no helping with the above, but can we *please* try to get rid
> of this #define insanity before moving things around? I came up with
> the following, which seems to build.
>
> Thoughts?
>
> M.
>
> From 8a50c98489220d2ebaf02d4ffdbef3cf0d6634ee Mon Sep 17 00:00:00 2001
> From: Marc Zyngier <maz@kernel.org>
> Date: Thu, 7 Oct 2021 13:18:29 +0100
> Subject: [PATCH] KVM: arm64: Turn __KVM_HOST_SMCCC_FUNC_* into an enum
> (mostly)
>
> __KVM_HOST_SMCCC_FUNC_* is a royal pain, as there is a fair amount
> of churn around these #defines, and we avoid making it an enum
> only for the sake of the early init, low level code that requires
> __KVM_HOST_SMCCC_FUNC___kvm_hyp_init to be usable from assembly.
>
> Let's be brave and turn everything but this symbol into an enum,
> using a bit of arithmetic to avoid any overlap.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
> arch/arm64/include/asm/kvm_asm.h | 44 +++++++++++++++++---------------
> 1 file changed, 24 insertions(+), 20 deletions(-)
Looks fine to me:
Acked-by: Will Deacon <will@kernel.org>
Do you need me to respin my series on top of this?
Will
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2 5/5] KVM: arm64: Disable privileged hypercalls after pKVM finalisation
2021-10-08 7:27 ` Will Deacon
@ 2021-10-08 7:31 ` Marc Zyngier
0 siblings, 0 replies; 9+ messages in thread
From: Marc Zyngier @ 2021-10-08 7:31 UTC (permalink / raw)
To: Will Deacon
Cc: linux-arm-kernel, Quentin Perret, Catalin Marinas,
Alexandru Elisei, Suzuki K Poulose, Mark Rutland, kvmarm
On 2021-10-08 08:27, Will Deacon wrote:
> On Thu, Oct 07, 2021 at 01:56:47PM +0100, Marc Zyngier wrote:
>> On Tue, 05 Oct 2021 12:37:21 +0100,
>> Will Deacon <will@kernel.org> wrote:
>> >
>> This is no helping with the above, but can we *please* try to get rid
>> of this #define insanity before moving things around? I came up with
>> the following, which seems to build.
>>
>> Thoughts?
>>
>> M.
>>
>> From 8a50c98489220d2ebaf02d4ffdbef3cf0d6634ee Mon Sep 17 00:00:00 2001
>> From: Marc Zyngier <maz@kernel.org>
>> Date: Thu, 7 Oct 2021 13:18:29 +0100
>> Subject: [PATCH] KVM: arm64: Turn __KVM_HOST_SMCCC_FUNC_* into an enum
>> (mostly)
>>
>> __KVM_HOST_SMCCC_FUNC_* is a royal pain, as there is a fair amount
>> of churn around these #defines, and we avoid making it an enum
>> only for the sake of the early init, low level code that requires
>> __KVM_HOST_SMCCC_FUNC___kvm_hyp_init to be usable from assembly.
>>
>> Let's be brave and turn everything but this symbol into an enum,
>> using a bit of arithmetic to avoid any overlap.
>>
>> Signed-off-by: Marc Zyngier <maz@kernel.org>
>> ---
>> arch/arm64/include/asm/kvm_asm.h | 44
>> +++++++++++++++++---------------
>> 1 file changed, 24 insertions(+), 20 deletions(-)
>
> Looks fine to me:
>
> Acked-by: Will Deacon <will@kernel.org>
>
> Do you need me to respin my series on top of this?
If you don't mind, that'd make my life easier.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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^ permalink raw reply [flat|nested] 9+ messages in thread