From patchwork Tue Apr 21 00:41:51 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Gibson X-Patchwork-Id: 6245081 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 1B51CBF4A6 for ; Tue, 21 Apr 2015 00:42:26 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id EDB5D20259 for ; Tue, 21 Apr 2015 00:42:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ABD512024F for ; Tue, 21 Apr 2015 00:42:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751930AbbDUAmF (ORCPT ); Mon, 20 Apr 2015 20:42:05 -0400 Received: from ozlabs.org ([103.22.144.67]:51440 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750998AbbDUAmC (ORCPT ); Mon, 20 Apr 2015 20:42:02 -0400 Received: by ozlabs.org (Postfix, from userid 1007) id DD86A140142; Tue, 21 Apr 2015 10:41:59 +1000 (AEST) From: David Gibson To: agraf@suse.de, michael@ellerman.id.au, benh@kernel.crashing.org Cc: aik@ozlabs.ru, kvm-ppc@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, David Gibson Subject: [PATCHv4] kvmppc: Implement H_LOGICAL_CI_{LOAD,STORE} in KVM Date: Tue, 21 Apr 2015 10:41:51 +1000 Message-Id: <1429576911-6076-1-git-send-email-david@gibson.dropbear.id.au> X-Mailer: git-send-email 2.1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On POWER, storage caching is usually configured via the MMU - attributes such as cache-inhibited are stored in the TLB and the hashed page table. This makes correctly performing cache inhibited IO accesses awkward when the MMU is turned off (real mode). Some CPU models provide special registers to control the cache attributes of real mode load and stores but this is not at all consistent. This is a problem in particular for SLOF, the firmware used on KVM guests, which runs entirely in real mode, but which needs to do IO to load the kernel. To simplify this qemu implements two special hypercalls, H_LOGICAL_CI_LOAD and H_LOGICAL_CI_STORE which simulate a cache-inhibited load or store to a logical address (aka guest physical address). SLOF uses these for IO. However, because these are implemented within qemu, not the host kernel, these bypass any IO devices emulated within KVM itself. The simplest way to see this problem is to attempt to boot a KVM guest from a virtio-blk device with iothread / dataplane enabled. The iothread code relies on an in kernel implementation of the virtio queue notification, which is not triggered by the IO hcalls, and so the guest will stall in SLOF unable to load the guest OS. This patch addresses this by providing in-kernel implementations of the 2 hypercalls, which correctly scan the KVM IO bus. Any access to an address not handled by the KVM IO bus will cause a VM exit, hitting the qemu implementation as before. Note that a userspace change is also required, in order to enable these new hcall implementations with KVM_CAP_PPC_ENABLE_HCALL. Signed-off-by: David Gibson --- arch/powerpc/include/asm/kvm_book3s.h | 3 ++ arch/powerpc/kvm/book3s.c | 76 +++++++++++++++++++++++++++++++++++ arch/powerpc/kvm/book3s_hv.c | 12 ++++++ arch/powerpc/kvm/book3s_pr_papr.c | 28 +++++++++++++ 4 files changed, 119 insertions(+) Changes in v4: * Rebase onto 4.0+, correct for changed signature of kvm_io_bus_{read,write} Alex, I saw from some build system notifications that you seemed to hit some troubles compiling the last version of this patch. This should fix it - hope it's not too late to get into 4.1. diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h index 9930904..b91e74a 100644 --- a/arch/powerpc/include/asm/kvm_book3s.h +++ b/arch/powerpc/include/asm/kvm_book3s.h @@ -288,6 +288,9 @@ static inline bool kvmppc_supports_magic_page(struct kvm_vcpu *vcpu) return !is_kvmppc_hv_enabled(vcpu->kvm); } +extern int kvmppc_h_logical_ci_load(struct kvm_vcpu *vcpu); +extern int kvmppc_h_logical_ci_store(struct kvm_vcpu *vcpu); + /* Magic register values loaded into r3 and r4 before the 'sc' assembly * instruction for the OSI hypercalls */ #define OSI_SC_MAGIC_R3 0x113724FA diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c index cfbcdc6..453a8a4 100644 --- a/arch/powerpc/kvm/book3s.c +++ b/arch/powerpc/kvm/book3s.c @@ -821,6 +821,82 @@ void kvmppc_core_destroy_vm(struct kvm *kvm) #endif } +int kvmppc_h_logical_ci_load(struct kvm_vcpu *vcpu) +{ + unsigned long size = kvmppc_get_gpr(vcpu, 4); + unsigned long addr = kvmppc_get_gpr(vcpu, 5); + u64 buf; + int ret; + + if (!is_power_of_2(size) || (size > sizeof(buf))) + return H_TOO_HARD; + + ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, addr, size, &buf); + if (ret != 0) + return H_TOO_HARD; + + switch (size) { + case 1: + kvmppc_set_gpr(vcpu, 4, *(u8 *)&buf); + break; + + case 2: + kvmppc_set_gpr(vcpu, 4, be16_to_cpu(*(__be16 *)&buf)); + break; + + case 4: + kvmppc_set_gpr(vcpu, 4, be32_to_cpu(*(__be32 *)&buf)); + break; + + case 8: + kvmppc_set_gpr(vcpu, 4, be64_to_cpu(*(__be64 *)&buf)); + break; + + default: + BUG(); + } + + return H_SUCCESS; +} +EXPORT_SYMBOL_GPL(kvmppc_h_logical_ci_load); + +int kvmppc_h_logical_ci_store(struct kvm_vcpu *vcpu) +{ + unsigned long size = kvmppc_get_gpr(vcpu, 4); + unsigned long addr = kvmppc_get_gpr(vcpu, 5); + unsigned long val = kvmppc_get_gpr(vcpu, 6); + u64 buf; + int ret; + + switch (size) { + case 1: + *(u8 *)&buf = val; + break; + + case 2: + *(__be16 *)&buf = cpu_to_be16(val); + break; + + case 4: + *(__be32 *)&buf = cpu_to_be32(val); + break; + + case 8: + *(__be64 *)&buf = cpu_to_be64(val); + break; + + default: + return H_TOO_HARD; + } + + ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, addr, size, &buf); + if (ret != 0) + return H_TOO_HARD; + + return H_SUCCESS; +} +EXPORT_SYMBOL_GPL(kvmppc_h_logical_ci_store); + int kvmppc_core_check_processor_compat(void) { /* diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index de74756..b9c11a3 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -706,6 +706,16 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu) /* Send the error out to userspace via KVM_RUN */ return rc; + case H_LOGICAL_CI_LOAD: + ret = kvmppc_h_logical_ci_load(vcpu); + if (ret == H_TOO_HARD) + return RESUME_HOST; + break; + case H_LOGICAL_CI_STORE: + ret = kvmppc_h_logical_ci_store(vcpu); + if (ret == H_TOO_HARD) + return RESUME_HOST; + break; case H_SET_MODE: ret = kvmppc_h_set_mode(vcpu, kvmppc_get_gpr(vcpu, 4), kvmppc_get_gpr(vcpu, 5), @@ -740,6 +750,8 @@ static int kvmppc_hcall_impl_hv(unsigned long cmd) case H_CONFER: case H_REGISTER_VPA: case H_SET_MODE: + case H_LOGICAL_CI_LOAD: + case H_LOGICAL_CI_STORE: #ifdef CONFIG_KVM_XICS case H_XIRR: case H_CPPR: diff --git a/arch/powerpc/kvm/book3s_pr_papr.c b/arch/powerpc/kvm/book3s_pr_papr.c index ce3c893..f2c75a1 100644 --- a/arch/powerpc/kvm/book3s_pr_papr.c +++ b/arch/powerpc/kvm/book3s_pr_papr.c @@ -258,6 +258,28 @@ static int kvmppc_h_pr_put_tce(struct kvm_vcpu *vcpu) return EMULATE_DONE; } +static int kvmppc_h_pr_logical_ci_load(struct kvm_vcpu *vcpu) +{ + long rc; + + rc = kvmppc_h_logical_ci_load(vcpu); + if (rc == H_TOO_HARD) + return EMULATE_FAIL; + kvmppc_set_gpr(vcpu, 3, rc); + return EMULATE_DONE; +} + +static int kvmppc_h_pr_logical_ci_store(struct kvm_vcpu *vcpu) +{ + long rc; + + rc = kvmppc_h_logical_ci_store(vcpu); + if (rc == H_TOO_HARD) + return EMULATE_FAIL; + kvmppc_set_gpr(vcpu, 3, rc); + return EMULATE_DONE; +} + static int kvmppc_h_pr_xics_hcall(struct kvm_vcpu *vcpu, u32 cmd) { long rc = kvmppc_xics_hcall(vcpu, cmd); @@ -290,6 +312,10 @@ int kvmppc_h_pr(struct kvm_vcpu *vcpu, unsigned long cmd) clear_bit(KVM_REQ_UNHALT, &vcpu->requests); vcpu->stat.halt_wakeup++; return EMULATE_DONE; + case H_LOGICAL_CI_LOAD: + return kvmppc_h_pr_logical_ci_load(vcpu); + case H_LOGICAL_CI_STORE: + return kvmppc_h_pr_logical_ci_store(vcpu); case H_XIRR: case H_CPPR: case H_EOI: @@ -323,6 +349,8 @@ int kvmppc_hcall_impl_pr(unsigned long cmd) case H_BULK_REMOVE: case H_PUT_TCE: case H_CEDE: + case H_LOGICAL_CI_LOAD: + case H_LOGICAL_CI_STORE: #ifdef CONFIG_KVM_XICS case H_XIRR: case H_CPPR: