Re: [PATCH v2 5/5] KVM: arm64: Disable privileged hypercalls after pKVM finalisation
flat view
From: Marc Zyngier <maz@kernel.org>
Date: 2021-10-07 12:58:34
Also in:
kvmarm
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
On Tue, 05 Oct 2021 12:37:21 +0100, Will Deacon [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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 <redacted> 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)[]
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2.30.2
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Without deviation from the norm, progress is not possible.
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