From patchwork Fri Jan 18 21:20:24 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 10771563 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 223CB139A for ; Fri, 18 Jan 2019 21:22:38 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 13CE9305C8 for ; Fri, 18 Jan 2019 21:22:38 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1225E305EE; Fri, 18 Jan 2019 21:22:38 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 84CF1305F5 for ; Fri, 18 Jan 2019 21:22:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729763AbfARVWf (ORCPT ); Fri, 18 Jan 2019 16:22:35 -0500 Received: from mga05.intel.com ([192.55.52.43]:43594 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729615AbfARVWH (ORCPT ); Fri, 18 Jan 2019 16:22:07 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Jan 2019 13:22:06 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,492,1539673200"; d="scan'208";a="139511474" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.14]) by fmsmga001.fm.intel.com with ESMTP; 18 Jan 2019 13:22:06 -0800 From: Sean Christopherson To: Paolo Bonzini , =?utf-8?b?UmFkaW0gS3LEjW3DocWZ?= Cc: kvm@vger.kernel.org, Andi Kleen , Josh Poimboeuf Subject: [PATCH 16/29] KVM: VMX: Update VMCS.HOST_RSP via helper C function Date: Fri, 18 Jan 2019 13:20:24 -0800 Message-Id: <20190118212037.24412-17-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190118212037.24412-1-sean.j.christopherson@intel.com> References: <20190118212037.24412-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Providing a helper function to update HOST_RSP is visibly easier to read, and more importantly (for the future) eliminates two arguments to the VM-Enter assembly blob. Reducing the number of arguments to the asm blob is for all intents and purposes a prerequisite to moving the code to a proper assembly routine. It's not truly mandatory, but it greatly simplifies the future code, and the cost of the extra CALL+RET is negligible in the grand scheme. Tweak the comment about clearing "clobbered" registers. The trigger isn't actually whether a register is marked as clobbered, but whether it will hold a guest value at the end of the asm blob. This matters now that RCX is clobbered but holds a host-defined value. Note that although _ASM_ARG[1-3] can be used in the inline asm itself, the intput/output constraints need to be manually defined. gcc will actually compile with _ASM_ARG[1-3] specified as constraints, but what it actually ends up doing with the bogus constraint is unknown. Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/vmx.c | 55 +++++++++++++++++++++--------------------- 1 file changed, 28 insertions(+), 27 deletions(-) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index cbdda35ee839..c5e56231fb8a 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6362,15 +6362,18 @@ static void vmx_update_hv_timer(struct kvm_vcpu *vcpu) vmx->loaded_vmcs->hv_timer_armed = false; } +void vmx_update_host_rsp(struct vcpu_vmx *vmx, unsigned long host_rsp) +{ + if (unlikely(host_rsp != vmx->loaded_vmcs->host_state.rsp)) { + vmx->loaded_vmcs->host_state.rsp = host_rsp; + vmcs_writel(HOST_RSP, host_rsp); + } +} + static void __vmx_vcpu_run(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx) { - unsigned long evmcs_rsp; - vmx->__launched = vmx->loaded_vmcs->launched; - evmcs_rsp = static_branch_unlikely(&enable_evmcs) ? - (unsigned long)¤t_evmcs->host_rsp : 0; - if (static_branch_unlikely(&vmx_l1d_should_flush)) vmx_l1d_flush(vcpu); @@ -6381,21 +6384,14 @@ static void __vmx_vcpu_run(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx) /* Store host registers */ "push %%" _ASM_BP " \n\t" "sub $%c[wordsize], %%" _ASM_SP "\n\t" /* placeholder for guest RCX */ - "push %%" _ASM_CX " \n\t" - "sub $%c[wordsize], %%" _ASM_SP "\n\t" /* temporarily adjust RSP for CALL */ - "cmp %%" _ASM_SP ", (%%" _ASM_DI ") \n\t" - "je 1f \n\t" - "mov %%" _ASM_SP ", (%%" _ASM_DI ") \n\t" - /* Avoid VMWRITE when Enlightened VMCS is in use */ - "test %%" _ASM_SI ", %%" _ASM_SI " \n\t" - "jz 2f \n\t" - "mov %%" _ASM_SP ", (%%" _ASM_SI ") \n\t" - "jmp 1f \n\t" - "2: \n\t" - "mov $%c[HOST_RSP], %%" _ASM_DX " \n\t" - __ex("vmwrite %%" _ASM_SP ", %%" _ASM_DX) "\n\t" - "1: \n\t" - "add $%c[wordsize], %%" _ASM_SP "\n\t" /* un-adjust RSP */ + "push %%" _ASM_ARG1 " \n\t" + + /* Adjust RSP to account for the CALL to vmx_vmenter(). */ + "lea -%c[wordsize](%%" _ASM_SP "), %%" _ASM_ARG2 " \n\t" + "call vmx_update_host_rsp \n\t" + + /* Load the vcpu_vmx pointer to RCX. */ + "mov (%%" _ASM_SP "), %%" _ASM_CX " \n\t" /* Check if vmlaunch or vmresume is needed */ "cmpb $0, %c[launched](%%" _ASM_CX ") \n\t" @@ -6449,8 +6445,8 @@ static void __vmx_vcpu_run(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx) "mov %%r14, %c[r14](%%" _ASM_CX ") \n\t" "mov %%r15, %c[r15](%%" _ASM_CX ") \n\t" /* - * Clear host registers marked as clobbered to prevent - * speculative use. + * Clear registers that contain guest values and will not be + * restored to prevent speculative use of the guest's values. */ "xor %%r8d, %%r8d \n\t" "xor %%r9d, %%r9d \n\t" @@ -6467,11 +6463,16 @@ static void __vmx_vcpu_run(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx) "xor %%esi, %%esi \n\t" "xor %%edi, %%edi \n\t" "pop %%" _ASM_BP " \n\t" - : ASM_CALL_CONSTRAINT, "=D"((int){0}), "=S"((int){0}) - : "c"(vmx), "D"(&vmx->loaded_vmcs->host_state.rsp), "S"(evmcs_rsp), + : ASM_CALL_CONSTRAINT, +#ifdef CONFIG_X86_64 + "=D"((int){0}) + : "D"(vmx), +#else + "=a"((int){0}) + : "a"(vmx), +#endif [launched]"i"(offsetof(struct vcpu_vmx, __launched)), [fail]"i"(offsetof(struct vcpu_vmx, fail)), - [HOST_RSP]"i"(HOST_RSP), [rax]"i"(offsetof(struct vcpu_vmx, vcpu.arch.regs[VCPU_REGS_RAX])), [rbx]"i"(offsetof(struct vcpu_vmx, vcpu.arch.regs[VCPU_REGS_RBX])), [rcx]"i"(offsetof(struct vcpu_vmx, vcpu.arch.regs[VCPU_REGS_RCX])), @@ -6492,10 +6493,10 @@ static void __vmx_vcpu_run(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx) [wordsize]"i"(sizeof(ulong)) : "cc", "memory" #ifdef CONFIG_X86_64 - , "rax", "rbx", "rdx" + , "rax", "rbx", "rcx", "rdx", "rsi" , "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15" #else - , "eax", "ebx", "edx" + , "ebx", "ecx", "edx", "edi", "esi" #endif );