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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=vGZZU806BMsy2FlLEX9qIWyBhkIdFLM7BAbzd+ZcB1o=; b=Bd9xH6qhKvIusqHW+/xa1Me+OC6xFoQ6nlfiu3AI1btkO+DZ0zn34BrW+ZSGodVB+4 S38dW36Neq7nu+OG8z4w7u/MXi/b+zlP5LQfSfJtzlYhVUQbRl7Pk+8WMVuw2swX0Fsw BQRmTWV2qJyTnhvcIY43qociP7rWKX4dgeKy/5Ihmbejarw1e9tp89WBCB29QsKr0tNf 7XUoAvsxgMRkTe+No69Jer+j5Ui5kOG5MdOA+tewA7qMvRPTDa88ckIglOpVYycYCK7U DuG9R7c/2xwNuxltR+94IXyIKD3rJKwIDElZCIwrKdGTjTUy142ED+CbKy+DMVUAZyHw h6aA== X-Gm-Message-State: AOAM530gQZghTPMO/Px4dE8aNqt+iQj80TMMu0rp9M0QEtU3LVMNdJ+z 9NOkXOmtKjU6yPBPbL1WgCOjGJPXnfs= X-Google-Smtp-Source: ABdhPJw4vZR6Z2Okaohac4Pa1YhCKmEapI4LF/TQcl603TxBJtJMT+OMFzMRR1DDDIyHUfYHfgoynLi/62s= X-Received: from ascull.lon.corp.google.com ([2a00:79e0:d:109:4a0f:cfff:fe4a:6363]) (user=ascull job=sendgmr) by 2002:a0c:b2d4:: with SMTP id d20mr1990339qvf.1.1599141213911; Thu, 03 Sep 2020 06:53:33 -0700 (PDT) Date: Thu, 3 Sep 2020 14:52:59 +0100 In-Reply-To: <20200903135307.251331-1-ascull@google.com> Message-Id: <20200903135307.251331-11-ascull@google.com> Mime-Version: 1.0 References: <20200903135307.251331-1-ascull@google.com> X-Mailer: git-send-email 2.28.0.402.g5ffc5be6b7-goog Subject: [PATCH v3 10/18] KVM: arm64: Restore hyp when panicking in guest context From: Andrew Scull To: kvmarm@lists.cs.columbia.edu X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200903_095337_618484_C1CF9BA9 X-CRM114-Status: GOOD ( 19.26 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arm-kernel@lists.infradead.org, kernel-team@android.com, suzuki.poulose@arm.com, maz@kernel.org, Sudeep Holla , james.morse@arm.com, Andrew Scull , catalin.marinas@arm.com, will@kernel.org, julien.thierry.kdev@gmail.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org If the guest context is loaded when a panic is triggered, restore the hyp context so e.g. the shadow call stack works when hyp_panic() is called and SP_EL0 is valid when the host's panic() is called. Use the hyp context's __hyp_running_vcpu field to track when hyp transitions to and from the guest vcpu so the exception handlers know whether the context needs to be restored. Signed-off-by: Andrew Scull --- arch/arm64/include/asm/kvm_asm.h | 10 ++++++++++ arch/arm64/kvm/hyp/entry.S | 24 ++++++++++++++++++++++++ arch/arm64/kvm/hyp/hyp-entry.S | 5 ++--- arch/arm64/kvm/hyp/include/hyp/switch.h | 4 +++- arch/arm64/kvm/hyp/nvhe/host.S | 5 +++++ 5 files changed, 44 insertions(+), 4 deletions(-) diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h index 34ec1b558219..6c3e3b903343 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -226,6 +226,16 @@ extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ]; ldr \vcpu, [\ctxt, #HOST_CONTEXT_VCPU] .endm +.macro get_loaded_vcpu vcpu, ctxt + hyp_adr_this_cpu \ctxt, kvm_hyp_ctxt, \vcpu + ldr \vcpu, [\ctxt, #HOST_CONTEXT_VCPU] +.endm + +.macro set_loaded_vcpu vcpu, ctxt, tmp + hyp_adr_this_cpu \ctxt, kvm_hyp_ctxt, \tmp + str \vcpu, [\ctxt, #HOST_CONTEXT_VCPU] +.endm + /* * KVM extable for unexpected exceptions. * In the same format _asm_extable, but output to a different section so that diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S index 38cca690a6ff..4787fc82790c 100644 --- a/arch/arm64/kvm/hyp/entry.S +++ b/arch/arm64/kvm/hyp/entry.S @@ -86,6 +86,8 @@ alternative_else_nop_endif ret 1: + set_loaded_vcpu x0, x1, x2 + add x29, x0, #VCPU_CONTEXT // Macro ptrauth_switch_to_guest format: @@ -116,6 +118,26 @@ alternative_else_nop_endif eret sb +SYM_INNER_LABEL(__guest_exit_panic, SYM_L_GLOBAL) + // x2-x29,lr: vcpu regs + // vcpu x0-x1 on the stack + + // If the hyp context is loaded, go straight to hyp_panic + get_loaded_vcpu x0, x1 + cbz x0, hyp_panic + + // The hyp context is saved so make sure it is restored to allow + // hyp_panic to run at hyp and, subsequently, panic to run in the host. + // This makes use of __guest_exit to avoid duplication but sets the + // return address to tail call into hyp_panic. As a side effect, the + // current state is saved to the guest context but it will only be + // accurate if the guest had been completely restored. + hyp_adr_this_cpu x0, kvm_hyp_ctxt, x1 + adr x1, hyp_panic + str x1, [x0, #CPU_XREG_OFFSET(30)] + + get_vcpu_ptr x1, x0 + SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL) // x0: return code // x1: vcpu @@ -163,6 +185,8 @@ SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL) // Now restore the hyp regs restore_callee_saved_regs x2 + set_loaded_vcpu xzr, x1, x2 + alternative_if ARM64_HAS_RAS_EXTN // If we have the RAS extensions we can consume a pending error // without an unmask-SError and isb. The ESB-instruction consumed any diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S index f92489250dfc..bc9f53df46f5 100644 --- a/arch/arm64/kvm/hyp/hyp-entry.S +++ b/arch/arm64/kvm/hyp/hyp-entry.S @@ -145,7 +145,7 @@ el2_error: eret sb -.macro invalid_vector label, target = hyp_panic +.macro invalid_vector label, target = __guest_exit_panic .align 2 SYM_CODE_START(\label) b \target @@ -186,10 +186,9 @@ check_preamble_length 661b, 662b .macro invalid_vect target .align 7 661: - b \target nop + stp x0, x1, [sp, #-16]! 662: - ldp x0, x1, [sp], #16 b \target check_preamble_length 661b, 662b diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h index afe714056b97..821721b78ad9 100644 --- a/arch/arm64/kvm/hyp/include/hyp/switch.h +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h @@ -509,6 +509,7 @@ static inline void __set_host_arch_workaround_state(struct kvm_vcpu *vcpu) static inline void __kvm_unexpected_el2_exception(void) { + extern char __guest_exit_panic[]; unsigned long addr, fixup; struct exception_table_entry *entry, *end; unsigned long elr_el2 = read_sysreg(elr_el2); @@ -529,7 +530,8 @@ static inline void __kvm_unexpected_el2_exception(void) return; } - hyp_panic(); + /* Trigger a panic after restoring the hyp context. */ + write_sysreg(__guest_exit_panic, elr_el2); } #endif /* __ARM64_KVM_HYP_SWITCH_H__ */ diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S index 5a7380c342c8..d4e8b8084020 100644 --- a/arch/arm64/kvm/hyp/nvhe/host.S +++ b/arch/arm64/kvm/hyp/nvhe/host.S @@ -72,6 +72,11 @@ SYM_FUNC_END(__hyp_do_panic) .macro invalid_host_vect .align 7 + /* If a guest is loaded, panic out of it. */ + stp x0, x1, [sp, #-16]! + get_loaded_vcpu x0, x1 + cbnz x0, __guest_exit_panic + add sp, sp, #16 b hyp_panic .endm -- 2.28.0.402.g5ffc5be6b7-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel