Commit 7a440cc7 authored by Quentin Perret's avatar Quentin Perret Committed by Marc Zyngier
Browse files

KVM: arm64: Enable access to sanitized CPU features at EL2 



Introduce the infrastructure in KVM enabling to copy CPU feature
registers into EL2-owned data-structures, to allow reading sanitised
values directly at EL2 in nVHE.

Given that only a subset of these features are being read by the
hypervisor, the ones that need to be copied are to be listed under
<asm/kvm_cpufeature.h> together with the name of the nVHE variable that
will hold the copy. This introduces only the infrastructure enabling
this copy. The first users will follow shortly.

Signed-off-by: default avatarQuentin Perret <qperret@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-14-qperret@google.com
parent 8e17c662

arch/arm64/include/asm/cpufeature.h

+1 −0
Original line number Diff line number Diff line
@@ -607,6 +607,7 @@ void check_local_cpu_capabilities(void); 


u64 read_sanitised_ftr_reg(u32 id);

u64 __read_sysreg_by_encoding(u32 sys_id);

int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst);



static inline bool cpu_supports_mixed_endian_el0(void)

{

arch/arm64/include/asm/kvm_cpufeature.h

0 → 100644
+22 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only */

/*

 * Copyright (C) 2020 - Google LLC

 * Author: Quentin Perret <qperret@google.com>

 */



#ifndef __ARM64_KVM_CPUFEATURE_H__

#define __ARM64_KVM_CPUFEATURE_H__



#include <asm/cpufeature.h>



#include <linux/build_bug.h>



#if defined(__KVM_NVHE_HYPERVISOR__)

#define DECLARE_KVM_HYP_CPU_FTR_REG(name) extern struct arm64_ftr_reg name

#define DEFINE_KVM_HYP_CPU_FTR_REG(name) struct arm64_ftr_reg name

#else

#define DECLARE_KVM_HYP_CPU_FTR_REG(name) extern struct arm64_ftr_reg kvm_nvhe_sym(name)

#define DEFINE_KVM_HYP_CPU_FTR_REG(name) BUILD_BUG()

#endif



#endif

arch/arm64/include/asm/kvm_host.h

+4 −0
Original line number Diff line number Diff line
@@ -740,9 +740,13 @@ void kvm_clr_pmu_events(u32 clr); 


void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu);

void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu);



void setup_kvm_el2_caps(void);

#else

static inline void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr) {}

static inline void kvm_clr_pmu_events(u32 clr) {}



static inline void setup_kvm_el2_caps(void) {}

#endif



void kvm_vcpu_load_sysregs_vhe(struct kvm_vcpu *vcpu);

arch/arm64/kernel/cpufeature.c

+13 −0
Original line number Diff line number Diff line
@@ -1154,6 +1154,18 @@ u64 read_sanitised_ftr_reg(u32 id) 
}

EXPORT_SYMBOL_GPL(read_sanitised_ftr_reg);



int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst)

{

	struct arm64_ftr_reg *regp = get_arm64_ftr_reg(id);



	if (!regp)

		return -EINVAL;



	*dst = *regp;



	return 0;

}



#define read_sysreg_case(r)	\

	case r:		val = read_sysreg_s(r); break;
@@ -2773,6 +2785,7 @@ void __init setup_cpu_features(void) 


	setup_system_capabilities();

	setup_elf_hwcaps(arm64_elf_hwcaps);

	setup_kvm_el2_caps();



	if (system_supports_32bit_el0())

		setup_elf_hwcaps(compat_elf_hwcaps);

arch/arm64/kvm/sys_regs.c

+19 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include <asm/debug-monitors.h>

#include <asm/esr.h>

#include <asm/kvm_arm.h>

#include <asm/kvm_cpufeature.h>

#include <asm/kvm_emulate.h>

#include <asm/kvm_hyp.h>

#include <asm/kvm_mmu.h>
@@ -2775,3 +2776,21 @@ void kvm_sys_reg_table_init(void) 
	/* Clear all higher bits. */

	cache_levels &= (1 << (i*3))-1;

}



#define CPU_FTR_REG_HYP_COPY(id, name) \

	{ .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) }

struct __ftr_reg_copy_entry {

	u32			sys_id;

	struct arm64_ftr_reg	*dst;

} hyp_ftr_regs[] __initdata = {

};



void __init setup_kvm_el2_caps(void)

{

	int i;



	for (i = 0; i < ARRAY_SIZE(hyp_ftr_regs); i++) {

		WARN(copy_ftr_reg(hyp_ftr_regs[i].sys_id, hyp_ftr_regs[i].dst),

		     "%u feature register not found\n", hyp_ftr_regs[i].sys_id);

	}

}