From 5e0781df18990497f4cd96a959ca583d83b6d1e0 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 25 Jan 2019 07:41:12 -0800 Subject: [PATCH] KVM: VMX: Move vCPU-run code to a proper assembly routine As evidenced by the myriad patches leading up to this moment, using an inline asm blob for vCPU-run is nothing short of horrific. It's also been called "unholy", "an abomination" and likely a whole host of other names that would violate the Code of Conduct if recorded here and now. The code is relocated nearly verbatim, e.g. quotes, newlines, tabs and __stringify need to be dropped, but other than those cosmetic changes the only functional changees are to add the "call" and replace the final "jmp" with a "ret". Note that STACK_FRAME_NON_STANDARD is also dropped from __vmx_vcpu_run(). Suggested-by: Andi Kleen Suggested-by: Josh Poimboeuf Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/vmenter.S | 144 +++++++++++++++++++++++++++++++++++++ arch/x86/kvm/vmx/vmx.c | 138 +---------------------------------- 2 files changed, 145 insertions(+), 137 deletions(-) diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S index bcef2c7e9bc4..e64617f3b196 100644 --- a/arch/x86/kvm/vmx/vmenter.S +++ b/arch/x86/kvm/vmx/vmenter.S @@ -1,6 +1,30 @@ /* SPDX-License-Identifier: GPL-2.0 */ #include #include +#include +#include + +#define WORD_SIZE (BITS_PER_LONG / 8) + +#define VCPU_RAX __VCPU_REGS_RAX * WORD_SIZE +#define VCPU_RCX __VCPU_REGS_RCX * WORD_SIZE +#define VCPU_RDX __VCPU_REGS_RDX * WORD_SIZE +#define VCPU_RBX __VCPU_REGS_RBX * WORD_SIZE +/* Intentionally omit RSP as it's context switched by hardware */ +#define VCPU_RBP __VCPU_REGS_RBP * WORD_SIZE +#define VCPU_RSI __VCPU_REGS_RSI * WORD_SIZE +#define VCPU_RDI __VCPU_REGS_RDI * WORD_SIZE + +#ifdef CONFIG_X86_64 +#define VCPU_R8 __VCPU_REGS_R8 * WORD_SIZE +#define VCPU_R9 __VCPU_REGS_R9 * WORD_SIZE +#define VCPU_R10 __VCPU_REGS_R10 * WORD_SIZE +#define VCPU_R11 __VCPU_REGS_R11 * WORD_SIZE +#define VCPU_R12 __VCPU_REGS_R12 * WORD_SIZE +#define VCPU_R13 __VCPU_REGS_R13 * WORD_SIZE +#define VCPU_R14 __VCPU_REGS_R14 * WORD_SIZE +#define VCPU_R15 __VCPU_REGS_R15 * WORD_SIZE +#endif .text @@ -55,3 +79,123 @@ ENDPROC(vmx_vmenter) ENTRY(vmx_vmexit) ret ENDPROC(vmx_vmexit) + +/** + * ____vmx_vcpu_run - Run a vCPU via a transition to VMX guest mode + * @vmx: struct vcpu_vmx * + * @regs: unsigned long * (to guest registers) + * %RBX: VMCS launched status (non-zero indicates already launched) + * + * Returns: + * %RBX is 0 on VM-Exit, 1 on VM-Fail + */ +ENTRY(____vmx_vcpu_run) + push %_ASM_BP + mov %_ASM_SP, %_ASM_BP + + /* + * Save @regs, _ASM_ARG2 may be modified by vmx_update_host_rsp() and + * @regs is needed after VM-Exit to save the guest's register values. + */ + push %_ASM_ARG2 + + /* Adjust RSP to account for the CALL to vmx_vmenter(). */ + lea -WORD_SIZE(%_ASM_SP), %_ASM_ARG2 + call vmx_update_host_rsp + + /* Load @regs to RCX. */ + mov (%_ASM_SP), %_ASM_CX + + /* Check if vmlaunch or vmresume is needed */ + cmpb $0, %bl + + /* Load guest registers. Don't clobber flags. */ + mov VCPU_RAX(%_ASM_CX), %_ASM_AX + mov VCPU_RBX(%_ASM_CX), %_ASM_BX + mov VCPU_RDX(%_ASM_CX), %_ASM_DX + mov VCPU_RSI(%_ASM_CX), %_ASM_SI + mov VCPU_RDI(%_ASM_CX), %_ASM_DI + mov VCPU_RBP(%_ASM_CX), %_ASM_BP +#ifdef CONFIG_X86_64 + mov VCPU_R8 (%_ASM_CX), %r8 + mov VCPU_R9 (%_ASM_CX), %r9 + mov VCPU_R10(%_ASM_CX), %r10 + mov VCPU_R11(%_ASM_CX), %r11 + mov VCPU_R12(%_ASM_CX), %r12 + mov VCPU_R13(%_ASM_CX), %r13 + mov VCPU_R14(%_ASM_CX), %r14 + mov VCPU_R15(%_ASM_CX), %r15 +#endif + /* Load guest RCX. This kills the vmx_vcpu pointer! */ + mov VCPU_RCX(%_ASM_CX), %_ASM_CX + + /* Enter guest mode */ + call vmx_vmenter + + /* Jump on VM-Fail. */ + jbe 2f + + /* Temporarily save guest's RCX. */ + push %_ASM_CX + + /* Reload @regs to RCX. */ + mov WORD_SIZE(%_ASM_SP), %_ASM_CX + + /* Save all guest registers, including RCX from the stack */ + mov %_ASM_AX, VCPU_RAX(%_ASM_CX) + mov %_ASM_BX, VCPU_RBX(%_ASM_CX) + __ASM_SIZE(pop) VCPU_RCX(%_ASM_CX) + mov %_ASM_DX, VCPU_RDX(%_ASM_CX) + mov %_ASM_SI, VCPU_RSI(%_ASM_CX) + mov %_ASM_DI, VCPU_RDI(%_ASM_CX) + mov %_ASM_BP, VCPU_RBP(%_ASM_CX) +#ifdef CONFIG_X86_64 + mov %r8, VCPU_R8 (%_ASM_CX) + mov %r9, VCPU_R9 (%_ASM_CX) + mov %r10, VCPU_R10(%_ASM_CX) + mov %r11, VCPU_R11(%_ASM_CX) + mov %r12, VCPU_R12(%_ASM_CX) + mov %r13, VCPU_R13(%_ASM_CX) + mov %r14, VCPU_R14(%_ASM_CX) + mov %r15, VCPU_R15(%_ASM_CX) +#endif + + /* Clear EBX to indicate VM-Exit (as opposed to VM-Fail). */ + xor %ebx, %ebx + + /* + * Clear all general purpose registers except RSP and RBX to prevent + * speculative use of the guest's values, even those that are reloaded + * via the stack. In theory, an L1 cache miss when restoring registers + * could lead to speculative execution with the guest's values. + * Zeroing XORs are dirt cheap, i.e. the extra paranoia is essentially + * free. RSP and RBX are exempt as RSP is restored by hardware during + * VM-Exit and RBX is explicitly loaded with 0 or 1 to "return" VM-Fail. + */ +1: +#ifdef CONFIG_X86_64 + xor %r8d, %r8d + xor %r9d, %r9d + xor %r10d, %r10d + xor %r11d, %r11d + xor %r12d, %r12d + xor %r13d, %r13d + xor %r14d, %r14d + xor %r15d, %r15d +#endif + xor %eax, %eax + xor %ecx, %ecx + xor %edx, %edx + xor %esi, %esi + xor %edi, %edi + xor %ebp, %ebp + + /* "POP" @regs. */ + add $WORD_SIZE, %_ASM_SP + pop %_ASM_BP + ret + + /* VM-Fail. Out-of-line to avoid a taken Jcc after VM-Exit. */ +2: mov $1, %ebx + jmp 1b +ENDPROC(____vmx_vcpu_run) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 52fea89732db..0e6e2dd6265e 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6371,33 +6371,6 @@ void vmx_update_host_rsp(struct vcpu_vmx *vmx, unsigned long host_rsp) } } -#ifdef CONFIG_X86_64 -#define WORD_SIZE 8 -#else -#define WORD_SIZE 4 -#endif - -#define _WORD_SIZE __stringify(WORD_SIZE) - -#define VCPU_RAX __stringify(__VCPU_REGS_RAX * WORD_SIZE) -#define VCPU_RCX __stringify(__VCPU_REGS_RCX * WORD_SIZE) -#define VCPU_RDX __stringify(__VCPU_REGS_RDX * WORD_SIZE) -#define VCPU_RBX __stringify(__VCPU_REGS_RBX * WORD_SIZE) -/* Intentionally omit %RSP as it's context switched by hardware */ -#define VCPU_RBP __stringify(__VCPU_REGS_RBP * WORD_SIZE) -#define VCPU_RSI __stringify(__VCPU_REGS_RSI * WORD_SIZE) -#define VCPU_RDI __stringify(__VCPU_REGS_RDI * WORD_SIZE) -#ifdef CONFIG_X86_64 -#define VCPU_R8 __stringify(__VCPU_REGS_R8 * WORD_SIZE) -#define VCPU_R9 __stringify(__VCPU_REGS_R9 * WORD_SIZE) -#define VCPU_R10 __stringify(__VCPU_REGS_R10 * WORD_SIZE) -#define VCPU_R11 __stringify(__VCPU_REGS_R11 * WORD_SIZE) -#define VCPU_R12 __stringify(__VCPU_REGS_R12 * WORD_SIZE) -#define VCPU_R13 __stringify(__VCPU_REGS_R13 * WORD_SIZE) -#define VCPU_R14 __stringify(__VCPU_REGS_R14 * WORD_SIZE) -#define VCPU_R15 __stringify(__VCPU_REGS_R15 * WORD_SIZE) -#endif - static void __vmx_vcpu_run(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx) { if (static_branch_unlikely(&vmx_l1d_should_flush)) @@ -6407,115 +6380,7 @@ static void __vmx_vcpu_run(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx) write_cr2(vcpu->arch.cr2); asm( - "push %%" _ASM_BP " \n\t" - "mov %%" _ASM_SP ", %%" _ASM_BP " \n\t" - - /* - * Save @regs, _ASM_ARG2 may be modified by vmx_update_host_rsp() and - * @regs is needed after VM-Exit to save the guest's register values. - */ - "push %%" _ASM_ARG2 " \n\t" - - /* Adjust RSP to account for the CALL to vmx_vmenter(). */ - "lea -" _WORD_SIZE "(%%" _ASM_SP "), %%" _ASM_ARG2 " \n\t" - "call vmx_update_host_rsp \n\t" - - /* Load RCX with @regs. */ - "mov (%%" _ASM_SP "), %%" _ASM_CX " \n\t" - - /* Check if vmlaunch or vmresume is needed */ - "cmpb $0, %%bl \n\t" - - /* Load guest registers. Don't clobber flags. */ - "mov " VCPU_RAX "(%%" _ASM_CX "), %%" _ASM_AX " \n\t" - "mov " VCPU_RBX "(%%" _ASM_CX "), %%" _ASM_BX " \n\t" - "mov " VCPU_RDX "(%%" _ASM_CX "), %%" _ASM_DX " \n\t" - "mov " VCPU_RSI "(%%" _ASM_CX "), %%" _ASM_SI " \n\t" - "mov " VCPU_RDI "(%%" _ASM_CX "), %%" _ASM_DI " \n\t" - "mov " VCPU_RBP "(%%" _ASM_CX "), %%" _ASM_BP " \n\t" -#ifdef CONFIG_X86_64 - "mov " VCPU_R8 "(%%" _ASM_CX "), %%r8 \n\t" - "mov " VCPU_R9 "(%%" _ASM_CX "), %%r9 \n\t" - "mov " VCPU_R10 "(%%" _ASM_CX "), %%r10 \n\t" - "mov " VCPU_R11 "(%%" _ASM_CX "), %%r11 \n\t" - "mov " VCPU_R12 "(%%" _ASM_CX "), %%r12 \n\t" - "mov " VCPU_R13 "(%%" _ASM_CX "), %%r13 \n\t" - "mov " VCPU_R14 "(%%" _ASM_CX "), %%r14 \n\t" - "mov " VCPU_R15 "(%%" _ASM_CX "), %%r15 \n\t" -#endif - /* Load guest RCX. This kills the vmx_vcpu pointer! */ - "mov " VCPU_RCX"(%%" _ASM_CX "), %%" _ASM_CX " \n\t" - - /* Enter guest mode */ - "call vmx_vmenter\n\t" - "jbe 2f \n\t" - - /* Temporarily save guest's RCX. */ - "push %%" _ASM_CX " \n\t" - - /* Reload RCX with @regs. */ - "mov " _WORD_SIZE "(%%" _ASM_SP "), %%" _ASM_CX " \n\t" - - /* Save all guest registers, including RCX from the stack */ - "mov %%" _ASM_AX ", " VCPU_RAX "(%%" _ASM_CX ") \n\t" - "mov %%" _ASM_BX ", " VCPU_RBX "(%%" _ASM_CX ") \n\t" - __ASM_SIZE(pop) " " VCPU_RCX "(%%" _ASM_CX ") \n\t" - "mov %%" _ASM_DX ", " VCPU_RDX "(%%" _ASM_CX ") \n\t" - "mov %%" _ASM_SI ", " VCPU_RSI "(%%" _ASM_CX ") \n\t" - "mov %%" _ASM_DI ", " VCPU_RDI "(%%" _ASM_CX ") \n\t" - "mov %%" _ASM_BP ", " VCPU_RBP "(%%" _ASM_CX ") \n\t" -#ifdef CONFIG_X86_64 - "mov %%r8, " VCPU_R8 "(%%" _ASM_CX ") \n\t" - "mov %%r9, " VCPU_R9 "(%%" _ASM_CX ") \n\t" - "mov %%r10, " VCPU_R10 "(%%" _ASM_CX ") \n\t" - "mov %%r11, " VCPU_R11 "(%%" _ASM_CX ") \n\t" - "mov %%r12, " VCPU_R12 "(%%" _ASM_CX ") \n\t" - "mov %%r13, " VCPU_R13 "(%%" _ASM_CX ") \n\t" - "mov %%r14, " VCPU_R14 "(%%" _ASM_CX ") \n\t" - "mov %%r15, " VCPU_R15 "(%%" _ASM_CX ") \n\t" -#endif - - /* Clear EBX to indicate VM-Exit (as opposed to VM-Fail). */ - "xor %%ebx, %%ebx \n\t" - - /* - * Clear all general purpose registers except RSP and RBX to prevent - * speculative use of the guest's values, even those that are reloaded - * via the stack. In theory, an L1 cache miss when restoring registers - * could lead to speculative execution with the guest's values. - * Zeroing XORs are dirt cheap, i.e. the extra paranoia is essentially - * free. RSP and RBX are exempt as RSP is restored by hardware during - * VM-Exit and RBX is explicitly loaded with 0 or 1 to "return" VM-Fail. - */ - "1: \n\t" -#ifdef CONFIG_X86_64 - "xor %%r8d, %%r8d \n\t" - "xor %%r9d, %%r9d \n\t" - "xor %%r10d, %%r10d \n\t" - "xor %%r11d, %%r11d \n\t" - "xor %%r12d, %%r12d \n\t" - "xor %%r13d, %%r13d \n\t" - "xor %%r14d, %%r14d \n\t" - "xor %%r15d, %%r15d \n\t" -#endif - "xor %%eax, %%eax \n\t" - "xor %%ecx, %%ecx \n\t" - "xor %%edx, %%edx \n\t" - "xor %%esi, %%esi \n\t" - "xor %%edi, %%edi \n\t" - "xor %%ebp, %%ebp \n\t" - - /* "POP" the vcpu_vmx pointer. */ - "add $" _WORD_SIZE ", %%" _ASM_SP " \n\t" - "pop %%" _ASM_BP " \n\t" - "jmp 3f \n\t" - - /* VM-Fail. Out-of-line to avoid a taken Jcc after VM-Exit. */ - "2: \n\t" - "mov $1, %%ebx \n\t" - "jmp 1b \n\t" - "3: \n\t" - + "call ____vmx_vcpu_run \n\t" : ASM_CALL_CONSTRAINT, "=b"(vmx->fail), #ifdef CONFIG_X86_64 "=D"((int){0}), "=S"((int){0}) @@ -6536,7 +6401,6 @@ static void __vmx_vcpu_run(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx) vcpu->arch.cr2 = read_cr2(); } -STACK_FRAME_NON_STANDARD(__vmx_vcpu_run); static void vmx_vcpu_run(struct kvm_vcpu *vcpu) { -- 2.45.2