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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=FjAmdHcCy7ece6Sz4HjhZ6GffgSinMrmw6yNTCSVSwk=; b=JsnnNepQO6Kfy0LFi3h2Sth9SEKOtfqRFpsj6DIG7XI+nkvACQMgFIvhGAZT9leymB RSlYqxuEem4oI7YwFUY3X7GvRi2nS4OIxbd/9cVtjb0acljChMTpyWOelzDDBPEgi9kV nTj3lkZ1WDdIHftIsa9JNaANBngwNnNPoxJl06KF4ueuQyVYMOs3i1CWM2yVo2ejUkqP PLMuLToHWkrz9d9LjgwZ0D79SsflQB6Oc9CjDhzhwPw6vnHjdMX1qhcY4aiAhNbDUvDQ 298j2GLnhO5sL830lPN/MDnjNC24thLtyxgFk4DeUx2NshnU7aJZV3fUgKSf5p0e5Moi OejQ== X-Gm-Message-State: AOAM530SZm8jvZWkPLtBKoq99KT7YSl0zyQ6MBPMiienC1NTf0ESyo2u Fr6TFjTCkOeqT9HcvvGUJoPeNPyAqI0= X-Google-Smtp-Source: ABdhPJxwgpm6jAly1zznwB2mChxPFf5CLS+C4Xqq/ymMDVdI5vF/UmDay3loY8j87L7qnbdGz7bkSvNWSyE= X-Received: from ascull.lon.corp.google.com ([2a00:79e0:d:109:4a0f:cfff:fe4a:6363]) (user=ascull job=sendgmr) by 2002:a17:906:edca:: with SMTP id sb10mr18951191ejb.60.1600166830976; Tue, 15 Sep 2020 03:47:10 -0700 (PDT) Date: Tue, 15 Sep 2020 11:46:34 +0100 In-Reply-To: <20200915104643.2543892-1-ascull@google.com> Message-Id: <20200915104643.2543892-11-ascull@google.com> Mime-Version: 1.0 References: <20200915104643.2543892-1-ascull@google.com> X-Mailer: git-send-email 2.28.0.618.gf4bc123cb7-goog Subject: [PATCH v4 10/19] 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-20200915_064716_496381_83A3C758 X-CRM114-Status: GOOD ( 19.32 ) X-Spam-Score: -7.7 (-------) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-7.7 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2a00:1450:4864:20:0:0:0:64a listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -7.5 USER_IN_DEF_DKIM_WL From: address is in the default DKIM white-list 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.0 DKIMWL_WL_MED DKIMwl.org - Medium sender 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 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.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 fe51c06d480d..4df2bd8882bc 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -236,6 +236,16 @@ 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 da21fddcef75..9ab7814e6114 100644 --- a/arch/arm64/kvm/hyp/nvhe/host.S +++ b/arch/arm64/kvm/hyp/nvhe/host.S @@ -75,6 +75,11 @@ 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