[PATCH v3 0/6] KVM: arm64: Restrict host hypercalls when pKVM is enabled

[PATCH v3 0/6] KVM: arm64: Restrict host hypercalls when pKVM is enabled

[Will Deacon]

Hi again folks,

This is version three of the patches I previously posted here:

  v1: https://lore.kernel.org/r/20210923112256.15767-1-will@kernel.org
  v2: https://lore.kernel.org/r/20211005113721.29441-1-will@kernel.org

Changes since v3 are:

  - Included proposed cleanup (using an enum) from Marc
  - Rebased onto -rc4

Cheers,

Will

Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Alexandru Elisei <alexandru.elisei@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: kvmarm@lists.cs.columbia.edu

--->8

Marc Zyngier (1):
  KVM: arm64: Turn __KVM_HOST_SMCCC_FUNC_* into an enum (mostly)

Will Deacon (5):
  arm64: Prevent kexec and hibernation if is_protected_kvm_enabled()
  KVM: arm64: Reject stub hypercalls after pKVM has been initialised
  KVM: arm64: Propagate errors from __pkvm_prot_finalize hypercall
  KVM: arm64: Prevent re-finalisation of pKVM for a given CPU
  KVM: arm64: Disable privileged hypercalls after pKVM finalisation

 arch/arm64/include/asm/kvm_asm.h      | 47 ++++++++++++---------
 arch/arm64/kernel/smp.c               |  3 +-
 arch/arm64/kvm/arm.c                  | 61 ++++++++++++++++++---------
 arch/arm64/kvm/hyp/nvhe/host.S        | 26 ++++++++----
 arch/arm64/kvm/hyp/nvhe/hyp-main.c    | 37 +++++++++++-----
 arch/arm64/kvm/hyp/nvhe/mem_protect.c |  3 ++
 6 files changed, 117 insertions(+), 60 deletions(-)

-- 
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[PATCH v3 1/6] KVM: arm64: Turn __KVM_HOST_SMCCC_FUNC_* into an enum (mostly)

[Will Deacon]

From: Marc Zyngier <maz@kernel.org>

__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.

Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/877depq9gw.wl-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Will Deacon <will@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)[]
 
-- 
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[PATCH v3 2/6] arm64: Prevent kexec and hibernation if is_protected_kvm_enabled()

[Will Deacon]

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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[PATCH v3 3/6] KVM: arm64: Reject stub hypercalls after pKVM has been initialised

[Will Deacon]

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>
Cc: 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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[PATCH v3 4/6] KVM: arm64: Propagate errors from __pkvm_prot_finalize hypercall

[Will Deacon]

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)
-- 
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[PATCH v3 5/6] KVM: arm64: Prevent re-finalisation of pKVM for a given CPU

[Will Deacon]

__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>
Cc: 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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[PATCH v3 6/6] KVM: arm64: Disable privileged hypercalls after pKVM finalisation

[Will Deacon]

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   | 25 +++++++++++---------
 arch/arm64/kvm/hyp/nvhe/hyp-main.c | 37 +++++++++++++++++++++---------
 2 files changed, 40 insertions(+), 22 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 43b5e213ae43..4654d27fd221 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -50,27 +50,30 @@
 #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_vcpu_run = __KVM_HOST_SMCCC_FUNC___kvm_hyp_init + 1,
+	__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___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[]
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];
-- 
2.33.0.882.g93a45727a2-goog


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Re: [PATCH v3 0/6] KVM: arm64: Restrict host hypercalls when pKVM is enabled

[Marc Zyngier]

On Fri, 8 Oct 2021 14:58:33 +0100, Will Deacon wrote:
> This is version three of the patches I previously posted here:
> 
>   v1: https://lore.kernel.org/r/20210923112256.15767-1-will@kernel.org
>   v2: https://lore.kernel.org/r/20211005113721.29441-1-will@kernel.org
> 
> Changes since v3 are:
> 
> [...]

Applied to next, thanks!

[1/6] KVM: arm64: Turn __KVM_HOST_SMCCC_FUNC_* into an enum (mostly)
      commit: a78738ed1d9bf40d09109599b884508c69d188b8
[2/6] arm64: Prevent kexec and hibernation if is_protected_kvm_enabled()
      commit: 8f4566f18db5d1257fc2d5442e16274424a529c1
[3/6] KVM: arm64: Reject stub hypercalls after pKVM has been initialised
      commit: 8579a185bacaa64c65e43e251ceede2f7600f7e2
[4/6] KVM: arm64: Propagate errors from __pkvm_prot_finalize hypercall
      commit: 2f2e1a5069679491d18cf9021da19b40c56a17f3
[5/6] KVM: arm64: Prevent re-finalisation of pKVM for a given CPU
      commit: 07036cffe17ec07e8fb630d86f8ea21832d9e57d
[6/6] KVM: arm64: Disable privileged hypercalls after pKVM finalisation
      commit: 057bed206f70d624c2eacb43ec56551950a26832

Cheers,

	M.
-- 
Without deviation from the norm, progress is not possible.



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