Invalidating translation lookaside buffer entries in a virtual machine (VM) system

Abstract

One embodiment of the present invention is a technique to invalidate entries in a translation lookaside buffer (TLB). A TLB in a processor has a plurality of TLB entries. Each TLB entry is associated with a virtual machine extension (VMX) tag word indicating if the associated TLB entry is invalidated according to a processor mode when an invalidation operation is performed. The processor mode is one of execution in a virtual machine (VM) and execution not in a virtual machine. The invalidation operation belongs to a non-empty set of invalidation operations composed of a union of (1) a possibly empty set of operations that invalidate a variable number of TLB entries, (2) a possibly empty set of operations that invalidate exactly one TLB entry, (3) a possibly empty set of operations that invalidate the plurality of TLB entries, (4) a possibly empty set of operations that enable and disable use of virtual memory, and (5) a possibly empty set of operations that configure physical address size, page size or other virtual memory system behavior in a manner that changes the manner in which a physical machine interprets the TLB entries.

1 . An apparatus comprising: 
 a translation lookaside buffer (TLB) in a processor having a plurality of TLB entries, each TLB entry being associated with a virtual machine extension (VMX) tag word indicating if the associated TLB entry is invalidated according to the processor mode when an invalidation operation is performed, the processor mode being one of execution in a virtual machine (VM) and execution not in a virtual machine, the invalidation operation belonging to a non-empty set of invalidation operations composed of a union of (1) a possibly empty set of operations that invalidate a variable number of TLB entries, (2) a possibly empty set of operations that invalidate exactly one TLB entry, (3) a possibly empty set of operations that invalidate the plurality of TLB entries, (4) a possibly empty set of operations that enable and disable use of virtual memory, and (5) a possibly empty set of operations that configure physical address size, page size or other virtual memory system behavior in a manner that changes the manner in which a physical machine interprets the TLB entries;    wherein the invalidation operations include IA-32-specific operations (a) IA-32 task switches involving changes of virtual memory related control registers, or (b) loading of control registers that modify IA-32-specific page size extension (PSE) and physical address extension (PAE).    
   
   
       2 . The apparatus of  claim 1  wherein the invalidation operation is one of (1) a loading of a first control register conditioned on a global bit, (2) an execution of a page invalidate instruction, (3) an IA-32 task switch involving change of at least one virtual memory related control register (4) a loading of a second control register that modifies one of a protected mode indicator and a page mode indicator, and (5) a loading of a third control register that modifies one of an IA-32-specific page size extension (PSE), a page global enable (PGE), and a physical address extension (PAE).  
   
   
       3 . The apparatus of  claim 2  wherein the processor is in or not in VMX mode and the TLB entry is not invalidated at loading of the first control register when one of a transition into VMX mode (a VM entrance) and a transition out of VMX mode (a VM exit) occurs.  
   
   
       4 . The apparatus of  claim 3  wherein the VMX tag word is a single bit and 
 the VMX tag word is negated for a new TLB entry when the processor is not in VMX mode and the VMX tag word is asserted for a new TLB entry when the processor is in VMX mode; and    the TLB entry is invalidated when an invalidation operation is performed and the VMX tag word is asserted and the processor is in VMX mode.    
   
   
       5 . The apparatus of  claim 4  wherein the TLB entry is invalidated irrespective of value of the VMX tag word when an invalidation operation is performed and the processor is not in VMX mode.  
   
   
       6 . The apparatus of  claim 4  wherein a field in a control register is designated the translation lookaside buffer virtual machine extension (TLBVMX) word and the TLB entry is invalidated when an invalidation operation is performed and the VMX tag word matches the TLBVMX word and the processor is not in VMX mode.  
   
   
       7 . The apparatus of  claim 3  wherein the VMX tag word is a single bit and 
 the VMX tag word is asserted for a new TLB entry when the processor is not in VMX mode and the VMX tag word is negated for a new TLB entry when the processor is in VMX mode; and    the TLB entry is invalidated when an invalidation operation is performed and the VMX tag word is negated and the processor is in VMX mode.    
   
   
       8 . The apparatus of  claim 7  wherein the TLB entry is invalidated irrespective of the value of the VMX tag word when an invalidation operation is performed and the processor is not in VMX mode.  
   
   
       9 . The apparatus of  claim 7  wherein a field in a control register is designated the TLBVMX word and the TLB entry is invalidated when an invalidation operation is performed and the VMX tag word matches the TLBVMX word and the processor is not in VMX mode.  
   
   
       10 . The apparatus of  claim 1  wherein invalidation of a TLB entry by an invalidation operation is further conditioned upon value of one or more control words associated with the TLB.  
   
   
       11 . The apparatus of  claim 10  wherein the control word or words associated with the TLB are located in one or more of the control registers of the processor or in a Virtual Machine Control Structure (VMCS) in memory.  
   
   
       12 . The apparatus of  claim 11  wherein one of the control words associated with the TLB is distinguished such that the VMX tag word is set to match a distinguished control word for a new TLB entry, the distinguished control word associated with the TLB being designated the TLBVMX word.  
   
   
       13 . The apparatus of  claim 12  wherein the TLBVMX word is set to one of a plurality of values that constitute a proper subset of a set of all possible values for a VMX tag word when the processor mode corresponds to execution in a virtual machine (VM).  
   
   
       14 . The apparatus of  claim 13  wherein the TLB entry is invalidated when an invalidation operation is performed and the value of the associated VMX tag word matches the value of the TLBVMX word and the processor mode corresponds to execution in a virtual machine (VM).  
   
   
       15 . The apparatus of  claim 14  wherein the one or more control words associated with the TLB, including the TLBVMX word, are configurable when the processor mode corresponds to execution not in a virtual machine.  
   
   
       16 . The apparatus of  claim 13  wherein the TLBVMX word is set to one of a plurality of values that constitute a proper subset of a set of all possible values for a VMX tag word when the processor mode corresponds to execution not in a virtual machine.  
   
   
       17 . The apparatus of  claim 16  wherein a set theoretic intersection of the plurality of values allowable for the TLBVMX word when the processor mode corresponds to execution not in a virtual machine and the plurality of values allowable for the TLBVMX word when the processor mode corresponds to execution in a virtual machine (VM) is an empty set.  
   
   
       18 . The apparatus of  claim 16  wherein invalidation of a TLB entry by an invalidation operation is further conditioned upon value of a second control word associated with the TLB when the processor mode corresponds to execution not in a virtual machine.  
   
   
       19 . The apparatus of  claim 18  wherein the TLB entry is invalidated when an invalidation operation is performed and the associated VMX tag word matches the second control word associated with the TLB and the processor mode corresponds to execution not in a virtual machine.  
   
   
       20 . The apparatus of  claim 18  wherein the TLB entry is invalidated when an invalidation operation is performed and the logical AND of the associated VMX tag word and the second control word associated with the TLB matches the TLBVMX word and the processor mode corresponds to execution in a virtual machine, the second control word associated with the TLB being designated the TLBVMX mask word.  
   
   
       21 . The apparatus of  claim 20  wherein access by software to configure a portion of the TLBVMX word when the processor mode corresponds to execution in a virtual machine (VM) is conditioned upon value of the TLBVMX mask word such that software executing when the processor mode corresponds to execution in a virtual machine (VM) is able to set the TLBVMX word to a value such that the logical AND of a new value of the TLBVMX word and a value of the TLBVMX mask word matches a logical AND of a previous value of the TLBVMX word and the value of TLBVMX mask word.  
   
   
       22 . (canceled)  
   
   
       23 . (canceled)  
   
   
       24 . (canceled)  
   
   
       25 . The apparatus of  claim 20  wherein the bits configured in the VMX tag word and the TLBVMX word are determined by an execution of a specified processor instruction in a specified manner.  
   
   
       26 . (canceled)  
   
   
       27 . The apparatus of  claim 18  wherein the TLB entry is invalidated when an invalidation operation is performed and the logical AND of the associated VMX tag word with a logical NOT of the second control word associated with the TLB matches the TLBVMX word and the processor mode corresponds to execution in a virtual machine (VM), the second control word associated with the TLB being designated the TLBVMX inverted mask word.  
   
   
       28 . The apparatus of  claim 27  wherein access by software to configure a portion of the TLBVMX word when the processor mode corresponds to execution in a virtual machine (VM) is conditioned upon the value of the TLBVMX inverted mask word such that software executing when the processor mode corresponds to execution in a virtual machine (VM) is able to set the TLBVMX word to a value such that a logical AND of a new value of the TLBVMX word and the logical NOT of the TLBVMX inverted mask word matches the logical AND of a previous value of the TLBVMX word and the logical NOT of TLBVMX inverted mask word.  
   
   
       29 . (canceled)  
   
   
       30 . (canceled)  
   
   
       31 . (canceled)  
   
   
       32 . (canceled)  
   
   
       33 . (canceled)  
   
   
       34 . The apparatus of  claim 16  wherein size of a VMX tag word and the TLBVMX word is determined by executing a specified processor instruction in a specified manner.  
   
   
       35 . The apparatus of  claim 34  wherein the processor is compatible with the Intel Architecture and the specified instruction is a CPUID instruction and the specified manner is to have a specified value in an EAX register when the CPUID instruction is executed.  
   
   
       36 . A method comprising: 
 associating a translation lookaside buffer (TLB) entry in a plurality of TLB entries in a processor with a virtual machine extension (VMX) tag word to indicate if the associated TLB entry is invalidated according to the processor mode when an invalidation operation is performed, the processor mode being one of execution in a virtual machine (VM) and execution not in a virtual machine; and    performing the invalidation operation, the invalidation operation belonging to a non-empty set of invalidation operations composed of a union of (1) a possibly empty set of operations that invalidate a variable number of TLB entries, (2) a possibly empty set of operations that invalidate exactly one TLB entry, (3) a possibly empty set of operations that invalidate the plurality of TLB entries, (4) a possibly empty set of operations that enable and disable use of virtual memory, and (5) a possibly empty set of operations that configure physical address size, page size or other virtual memory system behavior in a manner that changes the manner in which a physical machine interprets the TLB entries;    wherein the invalidation operations include IA-32-specific operations (a) IA-32 task switches involving changes of virtual memory related control registers, or (b) loading of control registers that modify IA-32-specific page size extension (PSE) and physical address extension (PAE).    
   
   
       37 . The method of  claim 36  wherein performing comprises performing the invalidation operation being one of (1) a loading of a first control register conditioned on a global bit, (2) an execution of a page invalidate instruction, (3) an IA-32 task switch involving change of at least one virtual memory related control register, (4) a loading of a second control register that modifies one of a protected mode indicator and a page mode indicator, and (5) a loading of a third control register that modifies one of an IA-32-specific page size extension (PSE), a page global enable (PGE), and a physical address extension (PAE).  
   
   
       38 . The method of  claim 37  wherein the processor is in or not in VMX mode and the TLB entry is not invalidated at loading of the first control register when one of a transition into VMX mode (a VM entrance) and a transition out of VMX mode (a VM exit) occurs.  
   
   
       39 . The method of  claim 38  further comprising: 
 negating the VMX tag word for a new TLB entry when the processor is not in VMX mode, the VMX tag word being a single bit;    asserting the VMX tag word for a new TLB entry when the processor is in VMX mode; and    invalidating the TLB entry when an invalidation operation is performed and the VMX tag word is asserted and the processor is in VMX mode.    
   
   
       40 . The method of  claim 39  wherein invalidating comprises invalidating the TLB entry irrespective of value of the VMX tag word when an invalidation operation is performed and the processor is not in VMX mode.  
   
   
       41 . The method of  claim 39  wherein invalidating comprises invalidating the TLB entry when an invalidation operation is performed and the VMX tag word matches the translation lookaside buffer virtual machine extension (TLBVMX) word and the processor is not in VMX mode, the TLBVMX word designating a field in a control register.  
   
   
       42 . The method of  claim 38  further comprising: 
 asserting the VMX tag word for a new TLB entry when the processor is not in VMX mode, the VMX tag word being a single bit;    negating the VMX tag word for a new TLB entry when the processor is in VMX mode; and    invalidating the TLB entry when an invalidation operation is performed and the VMX tag word is negated and the processor is in VMX mode.    
   
   
       43 . The method of  claim 42  wherein invalidating comprises invalidating the TLB entry irrespective of the value of the VMX tag word when an invalidation operation is performed and the processor is not in VMX mode.  
   
   
       44 . The method of  claim 42  wherein invalidating comprises invalidating the TLB entry when an invalidation operation is performed and the VMX tag word matches the TLBVMX word and the processor is not in VMX mode, the TLBVMX word designating a field in a control register.  
   
   
       45 . The method of  claim 42  wherein invalidating comprises invalidating the TLB entry by the invalidation operation conditioned upon value of one or more control words associated with the TLB.  
   
   
       46 . The method of  claim 45  wherein the control word or words associated with the TLB are located in one or more of the control registers of the processor or in a Virtual Machine Control Structure (VMCS) in memory.  
   
   
       47 . The method of  claim 46  further comprising distinguishing one of the control words associated with the TLB such that the VMX tag word is set to match a distinguished control word for a new TLB entry, the distinguished control word associated with the TLB being designated the TLBVMX word.  
   
   
       48 . The method of  claim 47  further comprising setting the TLBVMX word to one of a plurality of values that constitute a proper subset of a set of all possible values for a VMX tag word when the processor mode corresponds to execution in a virtual machine (VM).  
   
   
       49 . The method of  claim 48  wherein invalidating comprises invalidating the TLB entry when an invalidation operation is performed and the value of the associated VMX tag word matches the value of the TLBVMX word and the processor mode corresponds to execution in a virtual machine (VM).  
   
   
       50 . The method of  claim 49  further comprising configuring the one or more control words associated with the TLB, including the TLBVMX word, when the processor mode corresponds to execution not in a virtual machine.  
   
   
       51 . The method of  claim 48  further comprising setting the TLBVMX word to one of a plurality of values that constitute a proper subset of a set of all possible values for a VMX tag word when the processor mode corresponds to execution not in a virtual machine.  
   
   
       52 . The method of  claim 51  wherein a set theoretic intersection of the plurality of values allowable for the TLBVMX word when the processor mode corresponds to execution not in a virtual machine and the plurality of values allowable for the TLBVMX word when the processor mode corresponds to execution in a virtual machine (VM) is an empty set.  
   
   
       53 . The method of  claim 51  wherein invalidation of a TLB entry by an invalidation operation is further conditioned upon value of a second control word associated with the TLB when the processor mode corresponds to execution not in a virtual machine.  
   
   
       54 . The method of  claim 53  wherein invalidating comprises invalidating the TLB entry when an invalidation operation is performed and the associated VMX tag word matches the second control word associated with the TLB and the processor mode corresponds to execution not in a virtual machine.  
   
   
       55 . The method of  claim 53  wherein invalidating comprises invalidating the TLB entry when an invalidation operation is performed and the logical AND of the associated VMX tag word and the second control word associated with the TLB matches the TLBVMX word and the processor mode corresponds to execution in a virtual machine, the second control word associated with the TLB being designated the TLBVMX mask word.  
   
   
       56 . The method of  claim 55  further comprising accessing by software to configure a portion of the TLBVMX word when the processor mode corresponds to execution in a virtual machine (VM) conditioned upon value of the TLBVMX mask word such that software executing when the processor mode corresponds to execution in a virtual machine (VM) is able to set the TLBVMX word to a value such that the logical AND of a new value of the TLBVMX word and a value of the TLBVMX mask word matches a logical AND of a previous value of the TLBVMX word and the value of TLBVMX mask word.  
   
   
       57 . (canceled)  
   
   
       58 . (canceled)  
   
   
       59 . (canceled)  
   
   
       60 . (canceled)  
   
   
       61 . (canceled)  
   
   
       62 . The method of  claim 53  wherein invalidating comprises invalidating the TLB entry when an invalidation operation is performed and the logical AND of the associated VMX tag word with a logical NOT of the second control word associated with the TLB matches the TLBVMX word and the processor mode corresponds to execution in a virtual machine (VM), the second control word associated with the TLB being designated the TLBVMX inverted mask word.  
   
   
       63 . The method of  claim 62  further comprising accessing by software to configure a portion of the TLBVMX word when the processor mode corresponds to execution in a virtual machine (VM) conditioned upon the value of the TLBVMX inverted mask word such that software executing when the processor mode corresponds to execution in a virtual machine (VM) is able to set the TLBVMX word to a value such that a logical AND of a new value of the TLBVMX word and the logical NOT of the TLBVMX inverted mask word matches the logical AND of a previous value of the TLBVMX word and the logical NOT of TLBVMX inverted mask word.  
   
   
       64 . (canceled)  
   
   
       65 . (canceled)  
   
   
       66 . (canceled)  
   
   
       67 . (canceled)  
   
   
       68 . (canceled)  
   
   
       69 . The method of  claim 51  wherein determining comprises determining size of a VMX tag word and the TLBVMX word by executing a specified processor instruction in a specified manner.  
   
   
       70 . The method of  claim 69  wherein the processor is compatible with the Intel Architecture and the specified instruction is a CPUID instruction and the specified manner is to have a specified value in an EAX register when the CPUID instruction is executed.  
   
   
       71 . A processor comprising: 
 a translation lookaside buffer (TLB) having a plurality of TLB entries, each TLB entry being associated with a virtual machine extension (VMX) tag word indicating if the associated TLB entry is invalidated according to the processor mode when an invalidation operation is performed, the processor mode being one of execution in a virtual machine (VM) and execution not in a virtual machine, the invalidation operation belonging to a non-empty set of invalidation operations composed of a union of (1) a possibly empty set of operations that invalidate a variable number of TLB entries, (2) a possibly empty set of operations that invalidate exactly one TLB entry, (3) a possibly empty set of operations that invalidate the plurality of TLB entries, (4) a possibly empty set of operations that enable and disable use of virtual memory, and (5) a possibly empty set of operations that configure physical address size, page size or other virtual memory system behavior in a manner that changes the manner in which a physical machine interprets the TLB entries; and    first, second, and third registers coupled to the TLB to store information related to the invalidation operation    wherein the invalidation operations include IA-32-specific operations (a) IA-32 task switches involving changes of virtual memory related control registers, or (b) loading of control registers that modify IA-32-specific page size extension (PSE) and physical address extension (PAE).    
   
   
       72 . The processor of  claim 71  wherein the invalidation operation is one of (1) a loading of the first control register conditioned on a global bit, (2) an execution of a page invalidate instruction, (3) an IA-32 task switch involving change of at least one virtual memory related control register, and (5) a loading of the third control register that modifies one of an IA-32-specific page size extension (PSE), a page global enable (PGE), and a physical address extension (PAE).  
   
   
       73 . The processor of  claim 72  wherein the processor is in or not in VMX mode and the TLB entry is not invalidated at loading of the first control register when one of a transition into VMX mode (a VM entrance) and a transition out of VMX mode (a VM exit) occurs.  
   
   
       74 . The processor of  claim 73  wherein the VMX tag word is a single bit and 
 the VMX tag word is negated for a new TLB entry when the processor is not in VMX mode and the VMX tag word is asserted for a new TLB entry when the processor is in VMX mode; and    the TLB entry is invalidated when an invalidation operation is performed and the VMX tag word is asserted and the processor is in VMX mode.    
   
   
       75 . The processor of  claim 74  wherein the TLB entry is invalidated irrespective of value of the VMX tag word when an invalidation operation is performed and the processor is not in VMX mode.  
   
   
       76 . The processor of  claim 74  wherein a field in a control register is designated the translation lookaside buffer virtual machine extension (TLBVMX) word and the TLB entry is invalidated when an invalidation operation is performed and the VMX tag word matches the TLBVMX word and the processor is not in VMX mode.  
   
   
       77 . The processor of  claim 73  wherein the VMX tag word is a single bit and 
 the VMX tag word is asserted for a new TLB entry when the processor is not in VMX mode and the VMX tag word is negated for a new TLB entry when the processor is in VMX mode; and    the TLB entry is invalidated when an invalidation operation is performed and the VMX tag word is negated and the processor is in VMX mode.    
   
   
       78 . The processor of  claim 77  wherein the TLB entry is invalidated irrespective of the value of the VMX tag word when an invalidation operation is performed and the processor is not in VMX mode.  
   
   
       79 . The processor of  claim 77  wherein a field in a control register is designated the TLBVMX word and the TLB entry is invalidated when an invalidation operation is performed and the VMX tag word matches the TLBVMX word and the processor is not in VMX mode.  
   
   
       80 . (canceled)