From: Kristina Martsenko <kristina.martsenko@arm•com>
To: Amit Daniel Kachhap <amit.kachhap@arm•com>,
linux-arm-kernel@lists•infradead.org
Cc: Mark Rutland <mark.rutland@arm•com>,
Andrew Jones <drjones@redhat•com>,
Julien Thierry <julien.thierry@arm•com>,
Marc Zyngier <marc.zyngier@arm•com>,
Catalin Marinas <catalin.marinas@arm•com>,
Will Deacon <will.deacon@arm•com>,
Christoffer Dall <christoffer.dall@arm•com>,
kvmarm@lists•cs.columbia.edu, James Morse <james.morse@arm•com>,
Ramana Radhakrishnan <ramana.radhakrishnan@arm•com>,
Dave Martin <Dave.Martin@arm•com>,
linux-kernel@vger•kernel.org
Subject: Re: [PATCH v8 7/9] KVM: arm/arm64: context-switch ptrauth registers
Date: Thu, 4 Apr 2019 20:29:59 +0100 [thread overview]
Message-ID: <efe4fd6b-7f1f-c8b7-0667-e2bf636dcf4f@arm.com> (raw)
In-Reply-To: <1554172037-4516-8-git-send-email-amit.kachhap@arm.com>
On 02/04/2019 03:27, Amit Daniel Kachhap wrote:
> From: Mark Rutland <mark.rutland@arm•com>
>
> When pointer authentication is supported, a guest may wish to use it.
> This patch adds the necessary KVM infrastructure for this to work, with
> a semi-lazy context switch of the pointer auth state.
[...]
> diff --git a/arch/arm64/include/asm/kvm_ptrauth_asm.h b/arch/arm64/include/asm/kvm_ptrauth_asm.h
> new file mode 100644
> index 0000000..65f99e9
> --- /dev/null
> +++ b/arch/arm64/include/asm/kvm_ptrauth_asm.h
> @@ -0,0 +1,106 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* arch/arm64/include/asm/kvm_ptrauth_asm.h: Guest/host ptrauth save/restore
> + * Copyright 2019 Arm Limited
> + * Author: Mark Rutland <mark.rutland@arm•com>
> + * Amit Daniel Kachhap <amit.kachhap@arm•com>
> + */
> +
> +#ifndef __ASM_KVM_PTRAUTH_ASM_H
> +#define __ASM_KVM_PTRAUTH_ASM_H
> +
> +#ifndef __ASSEMBLY__
> +
> +#define __ptrauth_save_key(regs, key) \
> +({ \
> + regs[key ## KEYLO_EL1] = read_sysreg_s(SYS_ ## key ## KEYLO_EL1); \
> + regs[key ## KEYHI_EL1] = read_sysreg_s(SYS_ ## key ## KEYHI_EL1); \
> +})
> +
> +#define __ptrauth_save_state(ctxt) \
> +({ \
> + __ptrauth_save_key(ctxt->sys_regs, APIA); \
> + __ptrauth_save_key(ctxt->sys_regs, APIB); \
> + __ptrauth_save_key(ctxt->sys_regs, APDA); \
> + __ptrauth_save_key(ctxt->sys_regs, APDB); \
> + __ptrauth_save_key(ctxt->sys_regs, APGA); \
> +})
> +
> +#else /* __ASSEMBLY__ */
> +
> +#include <asm/sysreg.h>
> +
> +#ifdef CONFIG_ARM64_PTR_AUTH
> +
> +#define PTRAUTH_REG_OFFSET(x) (x - CPU_APIAKEYLO_EL1)
> +
> +/*
> + * CPU_AP*_EL1 values exceed immediate offset range (512) for stp instruction
> + * so below macros takes CPU_APIAKEYLO_EL1 as base and calculates the offset of
> + * the keys from this base to avoid an extra add instruction. These macros
> + * assumes the keys offsets are aligned in a specific increasing order.
> + */
> +.macro ptrauth_save_state base, reg1, reg2
> + mrs_s \reg1, SYS_APIAKEYLO_EL1
> + mrs_s \reg2, SYS_APIAKEYHI_EL1
> + stp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APIAKEYLO_EL1)]
> + mrs_s \reg1, SYS_APIBKEYLO_EL1
> + mrs_s \reg2, SYS_APIBKEYHI_EL1
> + stp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APIBKEYLO_EL1)]
> + mrs_s \reg1, SYS_APDAKEYLO_EL1
> + mrs_s \reg2, SYS_APDAKEYHI_EL1
> + stp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APDAKEYLO_EL1)]
> + mrs_s \reg1, SYS_APDBKEYLO_EL1
> + mrs_s \reg2, SYS_APDBKEYHI_EL1
> + stp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APDBKEYLO_EL1)]
> + mrs_s \reg1, SYS_APGAKEYLO_EL1
> + mrs_s \reg2, SYS_APGAKEYHI_EL1
> + stp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APGAKEYLO_EL1)]
> +.endm
> +
> +.macro ptrauth_restore_state base, reg1, reg2
> + ldp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APIAKEYLO_EL1)]
> + msr_s SYS_APIAKEYLO_EL1, \reg1
> + msr_s SYS_APIAKEYHI_EL1, \reg2
> + ldp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APIBKEYLO_EL1)]
> + msr_s SYS_APIBKEYLO_EL1, \reg1
> + msr_s SYS_APIBKEYHI_EL1, \reg2
> + ldp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APDAKEYLO_EL1)]
> + msr_s SYS_APDAKEYLO_EL1, \reg1
> + msr_s SYS_APDAKEYHI_EL1, \reg2
> + ldp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APDBKEYLO_EL1)]
> + msr_s SYS_APDBKEYLO_EL1, \reg1
> + msr_s SYS_APDBKEYHI_EL1, \reg2
> + ldp \reg1, \reg2, [\base, #PTRAUTH_REG_OFFSET(CPU_APGAKEYLO_EL1)]
> + msr_s SYS_APGAKEYLO_EL1, \reg1
> + msr_s SYS_APGAKEYHI_EL1, \reg2
> +.endm
> +
> +.macro ptrauth_switch_to_guest g_ctxt, reg1, reg2, reg3
> + ldr \reg1, [\g_ctxt, #CPU_HCR_EL2]
> + and \reg1, \reg1, #(HCR_API | HCR_APK)
> + cbz \reg1, 1f
> + add \reg1, \g_ctxt, #CPU_APIAKEYLO_EL1
> + ptrauth_restore_state \reg1, \reg2, \reg3
> +1:
Nit: the label in assembly macros is usually a larger number (see
assembler.h or alternative.h for example). I think this is to avoid
future accidents like
cbz x0, 1f
ptrauth_switch_to_guest x1, x2, x3, x4
add x5, x5, x6
1:
...
where the code would incorrectly branch to the label inside
ptrauth_switch_to_guest, instead of the one after it.
Thanks,
Kristina
> +.endm
> +
> +.macro ptrauth_switch_to_host g_ctxt, h_ctxt, reg1, reg2, reg3
> + ldr \reg1, [\g_ctxt, #CPU_HCR_EL2]
> + and \reg1, \reg1, #(HCR_API | HCR_APK)
> + cbz \reg1, 2f
> + add \reg1, \g_ctxt, #CPU_APIAKEYLO_EL1
> + ptrauth_save_state \reg1, \reg2, \reg3
> + add \reg1, \h_ctxt, #CPU_APIAKEYLO_EL1
> + ptrauth_restore_state \reg1, \reg2, \reg3
> + isb
> +2:
> +.endm
> +
> +#else /* !CONFIG_ARM64_PTR_AUTH */
> +.macro ptrauth_switch_to_guest g_ctxt, reg1, reg2, reg3
> +.endm
> +.macro ptrauth_switch_to_host g_ctxt, h_ctxt, reg1, reg2, reg3
> +.endm
> +#endif /* CONFIG_ARM64_PTR_AUTH */
> +#endif /* __ASSEMBLY__ */
> +#endif /* __ASM_KVM_PTRAUTH_ASM_H */
> diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
> index 675fdc1..3a70213 100644
> --- a/arch/arm64/kvm/hyp/entry.S
> +++ b/arch/arm64/kvm/hyp/entry.S
> @@ -24,6 +24,7 @@
> #include <asm/kvm_arm.h>
> #include <asm/kvm_asm.h>
> #include <asm/kvm_mmu.h>
> +#include <asm/kvm_ptrauth_asm.h>
>
> #define CPU_GP_REG_OFFSET(x) (CPU_GP_REGS + x)
> #define CPU_XREG_OFFSET(x) CPU_GP_REG_OFFSET(CPU_USER_PT_REGS + 8*x)
> @@ -64,6 +65,9 @@ ENTRY(__guest_enter)
>
> add x18, x0, #VCPU_CONTEXT
>
> + // Macro ptrauth_switch_to_guest(guest cxt, tmp1, tmp2, tmp3).
> + ptrauth_switch_to_guest x18, x0, x1, x2
> +
> // Restore guest regs x0-x17
> ldp x0, x1, [x18, #CPU_XREG_OFFSET(0)]
> ldp x2, x3, [x18, #CPU_XREG_OFFSET(2)]
> @@ -118,6 +122,9 @@ ENTRY(__guest_exit)
>
> get_host_ctxt x2, x3
>
> + // Macro ptrauth_switch_to_host(guest cxt, host cxt, tmp1, tmp2, tmp3).
> + ptrauth_switch_to_host x1, x2, x3, x4, x5
> +
> // Now restore the host regs
> restore_callee_saved_regs x2
>
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next prev parent reply other threads:[~2019-04-04 19:30 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-02 2:27 [PATCH v8 0/9] Add ARMv8.3 pointer authentication for kvm guest Amit Daniel Kachhap
2019-04-02 2:27 ` [PATCH v8 1/9] KVM: arm64: Propagate vcpu into read_id_reg() Amit Daniel Kachhap
2019-04-02 2:27 ` [PATCH v8 2/9] KVM: arm64: Support runtime sysreg visibility filtering Amit Daniel Kachhap
2019-04-02 2:27 ` [PATCH v8 3/9] KVM: arm64: Move hyp_symbol_addr to fix dependency Amit Daniel Kachhap
2019-04-05 11:02 ` Dave Martin
2019-04-08 3:42 ` Amit Daniel Kachhap
2019-04-02 2:27 ` [PATCH v8 4/9] KVM: arm/arm64: preserve host HCR_EL2 value Amit Daniel Kachhap
2019-04-05 11:02 ` Dave Martin
2019-04-08 4:31 ` Amit Daniel Kachhap
2019-04-06 10:37 ` James Morse
2019-04-08 13:05 ` Amit Daniel Kachhap
2019-04-08 18:39 ` Kristina Martsenko
2019-04-09 8:38 ` Marc Zyngier
2019-04-10 6:45 ` Amit Daniel Kachhap
2019-04-10 6:44 ` Amit Daniel Kachhap
2019-04-02 2:27 ` [PATCH v8 5/9] KVM: arm/arm64: preserve host MDCR_EL2 value Amit Daniel Kachhap
2019-04-05 11:02 ` Dave Martin
2019-04-08 4:39 ` Amit Daniel Kachhap
2019-04-02 2:27 ` [PATCH v8 6/9] KVM: arm64: Add vcpu feature flags to control ptrauth accessibility Amit Daniel Kachhap
2019-04-05 11:02 ` Dave Martin
2019-04-08 5:12 ` Amit Daniel Kachhap
2019-04-02 2:27 ` [PATCH v8 7/9] KVM: arm/arm64: context-switch ptrauth registers Amit Daniel Kachhap
2019-04-04 19:29 ` Kristina Martsenko [this message]
2019-04-05 11:00 ` Amit Daniel Kachhap
2019-04-02 2:27 ` [PATCH v8 8/9] KVM: arm64: Add capability to advertise ptrauth for guest Amit Daniel Kachhap
2019-04-05 11:03 ` Dave Martin
2019-04-08 8:51 ` Amit Daniel Kachhap
2019-04-02 2:27 ` [kvmtool PATCH v8 9/9] KVM: arm/arm64: Add a vcpu feature for pointer authentication Amit Daniel Kachhap
2019-04-05 11:04 ` Dave Martin
2019-04-08 8:43 ` Amit Daniel Kachhap
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