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Fri, 6 Oct 2017 12:39:21 +0100 (BST) From: =?UTF-8?q?Alex=20Benn=C3=A9e?= To: julien.thierry@arm.com, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, christoffer.dall@linaro.org, marc.zyngier@arm.com Subject: [PATCH v1 2/2] kvm: arm64: handle single-step of userspace mmio instructions Date: Fri, 6 Oct 2017 12:39:21 +0100 Message-Id: <20171006113921.24880-3-alex.bennee@linaro.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20171006113921.24880-1-alex.bennee@linaro.org> References: <20171006113921.24880-1-alex.bennee@linaro.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20171006_043947_029059_48C75307 X-CRM114-Status: GOOD ( 18.82 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Catalin Marinas , =?UTF-8?q?Alex=20Benn=C3=A9e?= , Russell King , Will Deacon , open list Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP The system state of KVM when using userspace emulation is not complete until we return into KVM_RUN. To handle mmio related updates we wait until they have been committed and then schedule our KVM_EXIT_DEBUG. I've introduced a new function kvm_arm_maybe_return_debug() to wrap up the differences between arm/arm64 which is currently null for arm. Signed-off-by: Alex Bennée Reviewed-by: Julien Thierry --- arch/arm/include/asm/kvm_host.h | 2 ++ arch/arm64/include/asm/kvm_host.h | 1 + arch/arm64/kvm/debug.c | 21 +++++++++++++++++++++ arch/arm64/kvm/handle_exit.c | 9 +++------ virt/kvm/arm/arm.c | 2 +- virt/kvm/arm/mmio.c | 3 ++- 6 files changed, 30 insertions(+), 8 deletions(-) diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h index 4a879f6ff13b..aec943f6d123 100644 --- a/arch/arm/include/asm/kvm_host.h +++ b/arch/arm/include/asm/kvm_host.h @@ -285,6 +285,8 @@ static inline void kvm_arm_init_debug(void) {} static inline void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) {} static inline void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) {} static inline void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu) {} +static inline int kvm_arm_maybe_return_debug(struct kvm_vcpu *vcpu, + struct kvm_run *run) {} int kvm_arm_vcpu_arch_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr); diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index e923b58606e2..fa67d21662f6 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -369,6 +369,7 @@ void kvm_arm_init_debug(void); void kvm_arm_setup_debug(struct kvm_vcpu *vcpu); void kvm_arm_clear_debug(struct kvm_vcpu *vcpu); void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu); +int kvm_arm_maybe_return_debug(struct kvm_vcpu *vcpu, struct kvm_run *run); int kvm_arm_vcpu_arch_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr); int kvm_arm_vcpu_arch_get_attr(struct kvm_vcpu *vcpu, diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c index dbadfaf850a7..a10a18c55c87 100644 --- a/arch/arm64/kvm/debug.c +++ b/arch/arm64/kvm/debug.c @@ -221,3 +221,24 @@ void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) } } } + + +/* + * When KVM has successfully emulated the instruction we might want to + * return we a KVM_EXIT_DEBUG. We can only do this once the emulation + * is complete though so for userspace emulations we have to wait + * until we have re-entered KVM. + * + * Return > 0 to return to guest, 0 (and set exit_reason) on proper + * exit to userspace. + */ + +int kvm_arm_maybe_return_debug(struct kvm_vcpu *vcpu, struct kvm_run *run) +{ + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { + run->exit_reason = KVM_EXIT_DEBUG; + run->debug.arch.hsr = ESR_ELx_EC_SOFTSTP_LOW << ESR_ELx_EC_SHIFT; + return 0; + } + return 1; +} diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index c918d291cb58..7b04f59217bf 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -202,13 +202,10 @@ static int handle_trap_exceptions(struct kvm_vcpu *vcpu, struct kvm_run *run) handled = exit_handler(vcpu, run); } - if (handled && (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)) { - handled = 0; - run->exit_reason = KVM_EXIT_DEBUG; - run->debug.arch.hsr = ESR_ELx_EC_SOFTSTP_LOW << ESR_ELx_EC_SHIFT; - } + if (handled) + return kvm_arm_maybe_return_debug(vcpu, run); - return handled; + return 0; } /* diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index b9f68e4add71..3d28fe2daa26 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -623,7 +623,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) if (run->exit_reason == KVM_EXIT_MMIO) { ret = kvm_handle_mmio_return(vcpu, vcpu->run); - if (ret) + if (ret < 1) return ret; } diff --git a/virt/kvm/arm/mmio.c b/virt/kvm/arm/mmio.c index b6e715fd3c90..e43e3bd6222f 100644 --- a/virt/kvm/arm/mmio.c +++ b/virt/kvm/arm/mmio.c @@ -117,7 +117,8 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run) vcpu_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data); } - return 0; + /* If debugging in effect we may need to return now */ + return kvm_arm_maybe_return_debug(vcpu, run); } static int decode_hsr(struct kvm_vcpu *vcpu, bool *is_write, int *len)