KVM: VMX: Optimize VMX instruction error and fault handling
Rework the VMX instruction helpers using asm-goto to branch directly
to error/fault "handlers" in lieu of using __ex(), i.e. the generic
____kvm_handle_fault_on_reboot(). Branching directly to fault handling
code during fixup avoids the extra JMP that is inserted after every VMX
instruction when using the generic "fault on reboot" (see commit
3901336ed9, "x86/kvm: Don't call kvm_spurious_fault() from .fixup").
Opportunistically clean up the helpers so that they all have consistent
error handling and messages.
Leave the usage of ____kvm_handle_fault_on_reboot() (via __ex()) in
kvm_cpu_vmxoff() and nested_vmx_check_vmentry_hw() as is. The VMXOFF
case is not a fast path, i.e. the cleanliness of __ex() is worth the
JMP, and the extra JMP in nested_vmx_check_vmentry_hw() is unavoidable.
Note, VMREAD cannot get the asm-goto treatment as output operands aren't
compatible with GCC's asm-goto due to internal compiler restrictions.
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
alistair/sunxi64-5.4-dsi
Sean Christopherson
Paolo Bonzini
parent
4b526de50e
commit
52a9fcbc73
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@ -14,6 +14,12 @@
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#define __ex_clear(x, reg) \
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____kvm_handle_fault_on_reboot(x, "xor " reg ", " reg)
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void vmwrite_error(unsigned long field, unsigned long value);
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void vmclear_error(struct vmcs *vmcs, u64 phys_addr);
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void vmptrld_error(struct vmcs *vmcs, u64 phys_addr);
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void invvpid_error(unsigned long ext, u16 vpid, gva_t gva);
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void invept_error(unsigned long ext, u64 eptp, gpa_t gpa);
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static __always_inline void vmcs_check16(unsigned long field)
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{
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BUILD_BUG_ON_MSG(__builtin_constant_p(field) && ((field) & 0x6001) == 0x2000,
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@ -103,21 +109,39 @@ static __always_inline unsigned long vmcs_readl(unsigned long field)
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return __vmcs_readl(field);
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}
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static noinline void vmwrite_error(unsigned long field, unsigned long value)
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{
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printk(KERN_ERR "vmwrite error: reg %lx value %lx (err %d)\n",
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field, value, vmcs_read32(VM_INSTRUCTION_ERROR));
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dump_stack();
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}
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#define vmx_asm1(insn, op1, error_args...) \
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do { \
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asm_volatile_goto("1: " __stringify(insn) " %0\n\t" \
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".byte 0x2e\n\t" /* branch not taken hint */ \
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"jna %l[error]\n\t" \
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_ASM_EXTABLE(1b, %l[fault]) \
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: : op1 : "cc" : error, fault); \
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return; \
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error: \
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insn##_error(error_args); \
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return; \
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fault: \
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kvm_spurious_fault(); \
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} while (0)
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#define vmx_asm2(insn, op1, op2, error_args...) \
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do { \
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asm_volatile_goto("1: " __stringify(insn) " %1, %0\n\t" \
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".byte 0x2e\n\t" /* branch not taken hint */ \
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"jna %l[error]\n\t" \
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_ASM_EXTABLE(1b, %l[fault]) \
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: : op1, op2 : "cc" : error, fault); \
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return; \
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error: \
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insn##_error(error_args); \
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return; \
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fault: \
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kvm_spurious_fault(); \
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} while (0)
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static __always_inline void __vmcs_writel(unsigned long field, unsigned long value)
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{
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bool error;
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asm volatile (__ex("vmwrite %2, %1") CC_SET(na)
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: CC_OUT(na) (error) : "r"(field), "rm"(value));
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if (unlikely(error))
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vmwrite_error(field, value);
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vmx_asm2(vmwrite, "r"(field), "rm"(value), field, value);
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}
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static __always_inline void vmcs_write16(unsigned long field, u16 value)
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@ -182,28 +206,18 @@ static __always_inline void vmcs_set_bits(unsigned long field, u32 mask)
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static inline void vmcs_clear(struct vmcs *vmcs)
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{
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u64 phys_addr = __pa(vmcs);
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bool error;
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asm volatile (__ex("vmclear %1") CC_SET(na)
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: CC_OUT(na) (error) : "m"(phys_addr));
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if (unlikely(error))
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printk(KERN_ERR "kvm: vmclear fail: %p/%llx\n",
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vmcs, phys_addr);
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vmx_asm1(vmclear, "m"(phys_addr), vmcs, phys_addr);
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}
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static inline void vmcs_load(struct vmcs *vmcs)
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{
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u64 phys_addr = __pa(vmcs);
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bool error;
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if (static_branch_unlikely(&enable_evmcs))
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return evmcs_load(phys_addr);
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asm volatile (__ex("vmptrld %1") CC_SET(na)
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: CC_OUT(na) (error) : "m"(phys_addr));
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if (unlikely(error))
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printk(KERN_ERR "kvm: vmptrld %p/%llx failed\n",
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vmcs, phys_addr);
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vmx_asm1(vmptrld, "m"(phys_addr), vmcs, phys_addr);
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}
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static inline void __invvpid(unsigned long ext, u16 vpid, gva_t gva)
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@ -213,11 +227,8 @@ static inline void __invvpid(unsigned long ext, u16 vpid, gva_t gva)
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u64 rsvd : 48;
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u64 gva;
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} operand = { vpid, 0, gva };
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bool error;
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asm volatile (__ex("invvpid %2, %1") CC_SET(na)
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: CC_OUT(na) (error) : "r"(ext), "m"(operand));
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BUG_ON(error);
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vmx_asm2(invvpid, "r"(ext), "m"(operand), ext, vpid, gva);
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}
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static inline void __invept(unsigned long ext, u64 eptp, gpa_t gpa)
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@ -225,11 +236,8 @@ static inline void __invept(unsigned long ext, u64 eptp, gpa_t gpa)
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struct {
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u64 eptp, gpa;
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} operand = {eptp, gpa};
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bool error;
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asm volatile (__ex("invept %2, %1") CC_SET(na)
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: CC_OUT(na) (error) : "r"(ext), "m"(operand));
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BUG_ON(error);
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vmx_asm2(invept, "r"(ext), "m"(operand), ext, eptp, gpa);
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}
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static inline bool vpid_sync_vcpu_addr(int vpid, gva_t addr)
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@ -343,6 +343,40 @@ static __always_inline void vmx_disable_intercept_for_msr(unsigned long *msr_bit
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void vmx_vmexit(void);
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#define vmx_insn_failed(fmt...) \
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do { \
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WARN_ONCE(1, fmt); \
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pr_warn_ratelimited(fmt); \
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} while (0)
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noinline void vmwrite_error(unsigned long field, unsigned long value)
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{
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vmx_insn_failed("kvm: vmwrite failed: field=%lx val=%lx err=%d\n",
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field, value, vmcs_read32(VM_INSTRUCTION_ERROR));
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}
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noinline void vmclear_error(struct vmcs *vmcs, u64 phys_addr)
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{
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vmx_insn_failed("kvm: vmclear failed: %p/%llx\n", vmcs, phys_addr);
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}
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noinline void vmptrld_error(struct vmcs *vmcs, u64 phys_addr)
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{
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vmx_insn_failed("kvm: vmptrld failed: %p/%llx\n", vmcs, phys_addr);
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}
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noinline void invvpid_error(unsigned long ext, u16 vpid, gva_t gva)
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{
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vmx_insn_failed("kvm: invvpid failed: ext=0x%lx vpid=%u gva=0x%lx\n",
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ext, vpid, gva);
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}
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noinline void invept_error(unsigned long ext, u64 eptp, gpa_t gpa)
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{
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vmx_insn_failed("kvm: invept failed: ext=0x%lx eptp=%llx gpa=0x%llx\n",
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ext, eptp, gpa);
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}
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static DEFINE_PER_CPU(struct vmcs *, vmxarea);
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DEFINE_PER_CPU(struct vmcs *, current_vmcs);
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/*
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