From: Quentin Perret <[email protected]> In preparation for removing the hyp code from the TCB, convert the current EL1 - EL2 KVM ABI to use hypercall numbers in lieu of direct function pointers. While this in itself does not provide any isolation, it is a first step towards having a properly defined EL2 ABI.
The implementation is based on a kvm_hcall_table which holds function pointers to the hyp_text functions corresponding to each hypercall. This is highly inspired from the arm64 sys_call_table, the main difference being the lack of hcall wrappers at this stage. Signed-off-by: Quentin Perret <[email protected]> Signed-off-by: David Brazdil <[email protected]> --- arch/arm64/include/asm/kvm_host.h | 20 ++++++- arch/arm64/include/asm/kvm_host_hypercalls.h | 62 ++++++++++++++++++++ arch/arm64/kvm/hyp/Makefile | 2 +- arch/arm64/kvm/hyp/host_hypercall.c | 22 +++++++ arch/arm64/kvm/hyp/hyp-entry.S | 36 +++++++++++- 5 files changed, 137 insertions(+), 5 deletions(-) create mode 100644 arch/arm64/include/asm/kvm_host_hypercalls.h create mode 100644 arch/arm64/kvm/hyp/host_hypercall.c diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index e61143d6602d..5dec3b06f2b7 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -24,6 +24,7 @@ #include <asm/fpsimd.h> #include <asm/kvm.h> #include <asm/kvm_asm.h> +#include <asm/kvm_host_hypercalls.h> #include <asm/thread_info.h> #include <asm/virt.h> @@ -447,10 +448,25 @@ int kvm_test_age_hva(struct kvm *kvm, unsigned long hva); void kvm_arm_halt_guest(struct kvm *kvm); void kvm_arm_resume_guest(struct kvm *kvm); -#define kvm_call_hyp_nvhe(hypfn, ...) \ - __kvm_call_hyp((unsigned long)kvm_ksym_ref(hypfn), ##__VA_ARGS__) +/* + * Call the hypervisor via HVC. The hcall parameter must be the name of + * a hypercall as defined in <asm/kvm_host_hypercall.h>. + * + * Hypercalls take at most 6 parameters. + */ +#define kvm_call_hyp_nvhe(hcall, ...) \ + __kvm_call_hyp(KVM_HOST_HCALL_NR(hcall), ##__VA_ARGS__) /* + * u64 kvm_call_hyp(hcall, ...); + * + * Call the hypervisor. The hcall parameter must be the name of a hypercall + * defined in <asm/kvm_host_hypercall.h>. In the VHE case, this will be + * translated into a direct function call. + * + * A hcall value of less than 0xfff has a special meaning and is used to + * implement hyp stubs in the same way as in arch/arm64/kernel/hyp_stub.S. + * * The couple of isb() below are there to guarantee the same behaviour * on VHE as on !VHE, where the eret to EL1 acts as a context * synchronization event. diff --git a/arch/arm64/include/asm/kvm_host_hypercalls.h b/arch/arm64/include/asm/kvm_host_hypercalls.h new file mode 100644 index 000000000000..af8ad505d816 --- /dev/null +++ b/arch/arm64/include/asm/kvm_host_hypercalls.h @@ -0,0 +1,62 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2020 Google, inc + */ + +#ifndef __KVM_HOST_HCALL +#define __KVM_HOST_HCALL(x) +#endif + +#define __KVM_HOST_HCALL_TABLE_IDX___kvm_enable_ssbs 0 +__KVM_HOST_HCALL(__kvm_enable_ssbs) + +#define __KVM_HOST_HCALL_TABLE_IDX___kvm_get_mdcr_el2 1 +__KVM_HOST_HCALL(__kvm_get_mdcr_el2) + +#define __KVM_HOST_HCALL_TABLE_IDX___kvm_timer_set_cntvoff 2 +__KVM_HOST_HCALL(__kvm_timer_set_cntvoff) + +#define __KVM_HOST_HCALL_TABLE_IDX___kvm_tlb_flush_local_vmid 3 +__KVM_HOST_HCALL(__kvm_tlb_flush_local_vmid) + +#define __KVM_HOST_HCALL_TABLE_IDX___kvm_flush_vm_context 4 +__KVM_HOST_HCALL(__kvm_flush_vm_context) + +#define __KVM_HOST_HCALL_TABLE_IDX___kvm_vcpu_run_nvhe 5 +__KVM_HOST_HCALL(__kvm_vcpu_run_nvhe) + +#define __KVM_HOST_HCALL_TABLE_IDX___kvm_tlb_flush_vmid 6 +__KVM_HOST_HCALL(__kvm_tlb_flush_vmid) + +#define __KVM_HOST_HCALL_TABLE_IDX___kvm_tlb_flush_vmid_ipa 7 +__KVM_HOST_HCALL(__kvm_tlb_flush_vmid_ipa) + +#define __KVM_HOST_HCALL_TABLE_IDX___vgic_v3_init_lrs 8 +__KVM_HOST_HCALL(__vgic_v3_init_lrs) + +#define __KVM_HOST_HCALL_TABLE_IDX___vgic_v3_get_ich_vtr_el2 9 +__KVM_HOST_HCALL(__vgic_v3_get_ich_vtr_el2) + +#define __KVM_HOST_HCALL_TABLE_IDX___vgic_v3_write_vmcr 10 +__KVM_HOST_HCALL(__vgic_v3_write_vmcr) + +#define __KVM_HOST_HCALL_TABLE_IDX___vgic_v3_restore_aprs 11 +__KVM_HOST_HCALL(__vgic_v3_restore_aprs) + +#define __KVM_HOST_HCALL_TABLE_IDX___vgic_v3_read_vmcr 12 +__KVM_HOST_HCALL(__vgic_v3_read_vmcr) + +#define __KVM_HOST_HCALL_TABLE_IDX___vgic_v3_save_aprs 13 +__KVM_HOST_HCALL(__vgic_v3_save_aprs) + +#define __KVM_HOST_HCALL_TABLE_IDX_SIZE 14 + +/* XXX - Arbitrary offset for KVM-related hypercalls */ +#define __KVM_HOST_HCALL_BASE_SHIFT 8 +#define __KVM_HOST_HCALL_BASE (1ULL << __KVM_HOST_HCALL_BASE_SHIFT) +#define __KVM_HOST_HCALL_END (__KVM_HOST_HCALL_BASE + \ + __KVM_HOST_HCALL_TABLE_IDX_SIZE) + +/* Hypercall number = kvm offset + table idx */ +#define KVM_HOST_HCALL_NR(name) (__KVM_HOST_HCALL_TABLE_IDX_##name + \ + __KVM_HOST_HCALL_BASE) diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile index 8c9880783839..29e2b2cd2fbc 100644 --- a/arch/arm64/kvm/hyp/Makefile +++ b/arch/arm64/kvm/hyp/Makefile @@ -9,7 +9,7 @@ ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING \ obj-$(CONFIG_KVM) += hyp.o hyp-y := vgic-v3-sr.o timer-sr.o aarch32.o vgic-v2-cpuif-proxy.o sysreg-sr.o \ - debug-sr.o entry.o switch.o fpsimd.o tlb.o hyp-entry.o + debug-sr.o entry.o switch.o fpsimd.o tlb.o host_hypercall.o hyp-entry.o # KVM code is run at a different exception code with a different map, so # compiler instrumentation that inserts callbacks or checks into the code may diff --git a/arch/arm64/kvm/hyp/host_hypercall.c b/arch/arm64/kvm/hyp/host_hypercall.c new file mode 100644 index 000000000000..6b31310f36a8 --- /dev/null +++ b/arch/arm64/kvm/hyp/host_hypercall.c @@ -0,0 +1,22 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2020 Google, inc + */ + +#include <asm/kvm_hyp.h> + +typedef long (*kvm_hcall_fn_t)(void); + +static long __hyp_text kvm_hc_ni(void) +{ + return -ENOSYS; +} + +#undef __KVM_HOST_HCALL +#define __KVM_HOST_HCALL(name) \ + [__KVM_HOST_HCALL_TABLE_IDX_##name] = (long (*)(void))name, + +const kvm_hcall_fn_t kvm_hcall_table[__KVM_HOST_HCALL_TABLE_IDX_SIZE] = { + [0 ... __KVM_HOST_HCALL_TABLE_IDX_SIZE-1] = kvm_hc_ni, +#include <asm/kvm_host_hypercalls.h> +}; diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S index c2a13ab3c471..1a51a0958504 100644 --- a/arch/arm64/kvm/hyp/hyp-entry.S +++ b/arch/arm64/kvm/hyp/hyp-entry.S @@ -13,6 +13,7 @@ #include <asm/kvm_arm.h> #include <asm/kvm_asm.h> #include <asm/kvm_mmu.h> +#include <asm/kvm_host_hypercalls.h> #include <asm/mmu.h> .text @@ -21,17 +22,26 @@ .macro do_el2_call /* * Shuffle the parameters before calling the function - * pointed to in x0. Assumes parameters in x[1,2,3]. + * pointed to in x0. Assumes parameters in x[1,2,3,4,5,6]. */ str lr, [sp, #-16]! mov lr, x0 mov x0, x1 mov x1, x2 mov x2, x3 + mov x3, x4 + mov x4, x5 + mov x5, x6 blr lr ldr lr, [sp], #16 .endm +/* kern_hyp_va(lm_alias(ksym)) */ +.macro ksym_hyp_va ksym, lm_offset + sub \ksym, \ksym, \lm_offset + kern_hyp_va \ksym +.endm + el1_sync: // Guest trapped into EL2 mrs x0, esr_el2 @@ -66,10 +76,32 @@ el1_sync: // Guest trapped into EL2 br x5 1: + /* Check if the hcall number is valid */ + cmp x0, #__KVM_HOST_HCALL_BASE + b.lt 2f + cmp x0, #__KVM_HOST_HCALL_END + b.lt 3f +2: + mov x0, -ENOSYS + eret + +3: + /* Compute lm_alias() offset in x9 */ + ldr_l x9, kimage_voffset + ldr_l x10, physvirt_offset + add x9, x9, x10 + + /* Find hcall function pointer in the table */ + ldr x10, =kvm_hcall_table + ksym_hyp_va x10, x9 + sub x0, x0, #__KVM_HOST_HCALL_BASE + add x0, x10, x0, lsl 3 + ldr x0, [x0] + ksym_hyp_va x0, x9 + /* * Perform the EL2 call */ - kern_hyp_va x0 do_el2_call eret -- 2.26.1 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
