From: Marc Zyngier <marc.zyngier@arm.com> To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu Cc: Will Deacon <will.deacon@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Thomas Gleixner <tglx@linutronix.de>, Andy Lutomirski <luto@kernel.org>, Kees Cook <keescook@chromium.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Christoffer Dall <christoffer.dall@arm.com> Subject: [PATCH 13/14] arm64: KVM: Handle guest's ARCH_WORKAROUND_2 requests Date: Tue, 22 May 2018 16:06:47 +0100 [thread overview] Message-ID: <20180522150648.28297-14-marc.zyngier@arm.com> (raw) In-Reply-To: <20180522150648.28297-1-marc.zyngier@arm.com> In order to forward the guest's ARCH_WORKAROUND_2 calls to EL3, add a small(-ish) sequence to handle it at EL2. Special care must be taken to track the state of the guest itself by updating the workaround flags. We also rely on patching to enable calls into the firmware. Note that since we need to execute branches, this always executes after the Spectre-v2 mitigation has been applied. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> --- arch/arm64/kernel/asm-offsets.c | 1 + arch/arm64/kvm/hyp/hyp-entry.S | 38 +++++++++++++++++++++++++++++++++++++- 2 files changed, 38 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index 5bdda651bd05..323aeb5f2fe6 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -136,6 +136,7 @@ int main(void) #ifdef CONFIG_KVM_ARM_HOST DEFINE(VCPU_CONTEXT, offsetof(struct kvm_vcpu, arch.ctxt)); DEFINE(VCPU_FAULT_DISR, offsetof(struct kvm_vcpu, arch.fault.disr_el1)); + DEFINE(VCPU_WORKAROUND_FLAGS, offsetof(struct kvm_vcpu, arch.workaround_flags)); DEFINE(CPU_GP_REGS, offsetof(struct kvm_cpu_context, gp_regs)); DEFINE(CPU_USER_PT_REGS, offsetof(struct kvm_regs, regs)); DEFINE(CPU_FP_REGS, offsetof(struct kvm_regs, fp_regs)); diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S index bffece27b5c1..5b1fa37ca1f4 100644 --- a/arch/arm64/kvm/hyp/hyp-entry.S +++ b/arch/arm64/kvm/hyp/hyp-entry.S @@ -106,8 +106,44 @@ el1_hvc_guest: */ ldr x1, [sp] // Guest's x0 eor w1, w1, #ARM_SMCCC_ARCH_WORKAROUND_1 + cbz w1, wa_epilogue + + /* ARM_SMCCC_ARCH_WORKAROUND_2 handling */ + eor w1, w1, #(ARM_SMCCC_ARCH_WORKAROUND_1 ^ \ + ARM_SMCCC_ARCH_WORKAROUND_2) cbnz w1, el1_trap - mov x0, x1 + +#ifdef CONFIG_ARM64_SSBD +alternative_cb arm64_enable_wa2_handling + b wa2_end +alternative_cb_end + get_vcpu_ptr x2, x0 + ldr x0, [x2, #VCPU_WORKAROUND_FLAGS] + + /* Sanitize the argument and update the guest flags*/ + ldr x1, [sp, #8] // Guest's x1 + clz w1, w1 // Murphy's device: + lsr w1, w1, #5 // w1 = !!w1 without using + eor w1, w1, #1 // the flags... + bfi x0, x1, #VCPU_WORKAROUND_2_FLAG_SHIFT, #1 + str x0, [x2, #VCPU_WORKAROUND_FLAGS] + + /* Check that we actually need to perform the call */ + hyp_ldr_this_cpu x0, arm64_ssbd_callback_required, x2 + cbz x0, wa2_end + + mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2 + smc #0 + + /* Don't leak data from the SMC call */ + mov x3, xzr +wa2_end: + mov x2, xzr + mov x1, xzr +#endif + +wa_epilogue: + mov x0, xzr add sp, sp, #16 eret -- 2.14.2
WARNING: multiple messages have this Message-ID (diff)
From: marc.zyngier@arm.com (Marc Zyngier) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 13/14] arm64: KVM: Handle guest's ARCH_WORKAROUND_2 requests Date: Tue, 22 May 2018 16:06:47 +0100 [thread overview] Message-ID: <20180522150648.28297-14-marc.zyngier@arm.com> (raw) In-Reply-To: <20180522150648.28297-1-marc.zyngier@arm.com> In order to forward the guest's ARCH_WORKAROUND_2 calls to EL3, add a small(-ish) sequence to handle it at EL2. Special care must be taken to track the state of the guest itself by updating the workaround flags. We also rely on patching to enable calls into the firmware. Note that since we need to execute branches, this always executes after the Spectre-v2 mitigation has been applied. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> --- arch/arm64/kernel/asm-offsets.c | 1 + arch/arm64/kvm/hyp/hyp-entry.S | 38 +++++++++++++++++++++++++++++++++++++- 2 files changed, 38 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index 5bdda651bd05..323aeb5f2fe6 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -136,6 +136,7 @@ int main(void) #ifdef CONFIG_KVM_ARM_HOST DEFINE(VCPU_CONTEXT, offsetof(struct kvm_vcpu, arch.ctxt)); DEFINE(VCPU_FAULT_DISR, offsetof(struct kvm_vcpu, arch.fault.disr_el1)); + DEFINE(VCPU_WORKAROUND_FLAGS, offsetof(struct kvm_vcpu, arch.workaround_flags)); DEFINE(CPU_GP_REGS, offsetof(struct kvm_cpu_context, gp_regs)); DEFINE(CPU_USER_PT_REGS, offsetof(struct kvm_regs, regs)); DEFINE(CPU_FP_REGS, offsetof(struct kvm_regs, fp_regs)); diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S index bffece27b5c1..5b1fa37ca1f4 100644 --- a/arch/arm64/kvm/hyp/hyp-entry.S +++ b/arch/arm64/kvm/hyp/hyp-entry.S @@ -106,8 +106,44 @@ el1_hvc_guest: */ ldr x1, [sp] // Guest's x0 eor w1, w1, #ARM_SMCCC_ARCH_WORKAROUND_1 + cbz w1, wa_epilogue + + /* ARM_SMCCC_ARCH_WORKAROUND_2 handling */ + eor w1, w1, #(ARM_SMCCC_ARCH_WORKAROUND_1 ^ \ + ARM_SMCCC_ARCH_WORKAROUND_2) cbnz w1, el1_trap - mov x0, x1 + +#ifdef CONFIG_ARM64_SSBD +alternative_cb arm64_enable_wa2_handling + b wa2_end +alternative_cb_end + get_vcpu_ptr x2, x0 + ldr x0, [x2, #VCPU_WORKAROUND_FLAGS] + + /* Sanitize the argument and update the guest flags*/ + ldr x1, [sp, #8] // Guest's x1 + clz w1, w1 // Murphy's device: + lsr w1, w1, #5 // w1 = !!w1 without using + eor w1, w1, #1 // the flags... + bfi x0, x1, #VCPU_WORKAROUND_2_FLAG_SHIFT, #1 + str x0, [x2, #VCPU_WORKAROUND_FLAGS] + + /* Check that we actually need to perform the call */ + hyp_ldr_this_cpu x0, arm64_ssbd_callback_required, x2 + cbz x0, wa2_end + + mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2 + smc #0 + + /* Don't leak data from the SMC call */ + mov x3, xzr +wa2_end: + mov x2, xzr + mov x1, xzr +#endif + +wa_epilogue: + mov x0, xzr add sp, sp, #16 eret -- 2.14.2
next prev parent reply other threads:[~2018-05-22 15:10 UTC|newest] Thread overview: 110+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-05-22 15:06 [PATCH 00/14] arm64 SSBD (aka Spectre-v4) mitigation Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-22 15:06 ` [PATCH 01/14] arm/arm64: smccc: Add SMCCC-specific return codes Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-24 10:55 ` Mark Rutland 2018-05-24 10:55 ` Mark Rutland 2018-05-22 15:06 ` [PATCH 02/14] arm64: Call ARCH_WORKAROUND_2 on transitions between EL0 and EL1 Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-23 9:23 ` Julien Grall 2018-05-23 9:23 ` Julien Grall 2018-05-24 10:52 ` Mark Rutland 2018-05-24 10:52 ` Mark Rutland 2018-05-24 12:10 ` Robin Murphy 2018-05-24 12:10 ` Robin Murphy 2018-05-24 11:00 ` Mark Rutland 2018-05-24 11:00 ` Mark Rutland 2018-05-24 11:23 ` Mark Rutland 2018-05-24 11:23 ` Mark Rutland 2018-05-24 11:28 ` Marc Zyngier 2018-05-24 11:28 ` Marc Zyngier 2018-05-22 15:06 ` [PATCH 03/14] arm64: Add per-cpu infrastructure to call ARCH_WORKAROUND_2 Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-23 10:03 ` Julien Grall 2018-05-23 10:03 ` Julien Grall 2018-05-24 11:14 ` Mark Rutland 2018-05-24 11:14 ` Mark Rutland 2018-05-22 15:06 ` [PATCH 04/14] arm64: Add ARCH_WORKAROUND_2 probing Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-23 10:06 ` Julien Grall 2018-05-23 10:06 ` Julien Grall 2018-05-24 9:58 ` Suzuki K Poulose 2018-05-24 9:58 ` Suzuki K Poulose 2018-05-24 11:39 ` Will Deacon 2018-05-24 11:39 ` Will Deacon 2018-05-24 13:34 ` Suzuki K Poulose 2018-05-24 13:34 ` Suzuki K Poulose 2018-05-24 11:27 ` Mark Rutland 2018-05-24 11:27 ` Mark Rutland 2018-05-22 15:06 ` [PATCH 05/14] arm64: Add 'ssbd' command-line option Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-22 15:29 ` Randy Dunlap 2018-05-22 15:29 ` Randy Dunlap 2018-05-22 15:29 ` Randy Dunlap 2018-05-23 10:08 ` Julien Grall 2018-05-23 10:08 ` Julien Grall 2018-05-24 11:40 ` Mark Rutland 2018-05-24 11:40 ` Mark Rutland 2018-05-24 11:52 ` Marc Zyngier 2018-05-24 11:52 ` Marc Zyngier 2018-05-22 15:06 ` [PATCH 06/14] arm64: ssbd: Add global mitigation state accessor Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-23 10:11 ` Julien Grall 2018-05-23 10:11 ` Julien Grall 2018-05-24 11:41 ` Mark Rutland 2018-05-24 11:41 ` Mark Rutland 2018-05-22 15:06 ` [PATCH 07/14] arm64: ssbd: Skip apply_ssbd if not using dynamic mitigation Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-23 10:13 ` Julien Grall 2018-05-23 10:13 ` Julien Grall 2018-05-24 11:43 ` Mark Rutland 2018-05-24 11:43 ` Mark Rutland 2018-05-22 15:06 ` [PATCH 08/14] arm64: ssbd: Disable mitigation on CPU resume if required by user Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-23 10:52 ` Julien Grall 2018-05-23 10:52 ` Julien Grall 2018-05-24 11:55 ` Mark Rutland 2018-05-24 11:55 ` Mark Rutland 2018-05-22 15:06 ` [PATCH 09/14] arm64: ssbd: Introduce thread flag to control userspace mitigation Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-24 12:01 ` Mark Rutland 2018-05-24 12:01 ` Mark Rutland 2018-05-24 12:16 ` Marc Zyngier 2018-05-24 12:16 ` Marc Zyngier 2018-05-24 12:19 ` Will Deacon 2018-05-24 12:19 ` Will Deacon 2018-05-24 12:36 ` Marc Zyngier 2018-05-24 12:36 ` Marc Zyngier 2018-05-22 15:06 ` [PATCH 10/14] arm64: ssbd: Add prctl interface for per-thread mitigation Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-22 15:48 ` Dominik Brodowski 2018-05-22 15:48 ` Dominik Brodowski 2018-05-22 16:30 ` Marc Zyngier 2018-05-22 16:30 ` Marc Zyngier 2018-05-22 16:30 ` Marc Zyngier 2018-05-24 12:10 ` Mark Rutland 2018-05-24 12:10 ` Mark Rutland 2018-05-24 12:24 ` Will Deacon 2018-05-24 12:24 ` Will Deacon 2018-05-22 15:06 ` [PATCH 11/14] arm64: KVM: Add HYP per-cpu accessors Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-24 12:11 ` Mark Rutland 2018-05-24 12:11 ` Mark Rutland 2018-05-22 15:06 ` [PATCH 12/14] arm64: KVM: Add ARCH_WORKAROUND_2 support for guests Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-24 12:15 ` Mark Rutland 2018-05-24 12:15 ` Mark Rutland 2018-05-22 15:06 ` Marc Zyngier [this message] 2018-05-22 15:06 ` [PATCH 13/14] arm64: KVM: Handle guest's ARCH_WORKAROUND_2 requests Marc Zyngier 2018-05-24 12:22 ` Mark Rutland 2018-05-24 12:22 ` Mark Rutland 2018-05-22 15:06 ` [PATCH 14/14] arm64: KVM: Add ARCH_WORKAROUND_2 discovery through ARCH_FEATURES_FUNC_ID Marc Zyngier 2018-05-22 15:06 ` Marc Zyngier 2018-05-24 12:25 ` Mark Rutland 2018-05-24 12:25 ` Mark Rutland 2018-07-20 9:47 [PATCH 00/14] arm64: 4.17 backport of the SSBD mitigation patches Marc Zyngier 2018-07-20 9:47 ` [PATCH 13/14] arm64: KVM: Handle guest's ARCH_WORKAROUND_2 requests Marc Zyngier
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