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authorLinus Torvalds <torvalds@linux-foundation.org>2012-10-04 09:30:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-04 09:30:33 -0700
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treeca8958900ad9e208a8e5fb7704f1b66dc76131b4 /Documentation/virtual/kvm/hypercalls.txt
parentce57e981f2b996aaca2031003b3f866368307766 (diff)
parent3d11df7abbff013b811d5615320580cd5d9d7d31 (diff)
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Merge tag 'kvm-3.7-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM updates from Avi Kivity: "Highlights of the changes for this release include support for vfio level triggered interrupts, improved big real mode support on older Intels, a streamlines guest page table walker, guest APIC speedups, PIO optimizations, better overcommit handling, and read-only memory." * tag 'kvm-3.7-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (138 commits) KVM: s390: Fix vcpu_load handling in interrupt code KVM: x86: Fix guest debug across vcpu INIT reset KVM: Add resampling irqfds for level triggered interrupts KVM: optimize apic interrupt delivery KVM: MMU: Eliminate pointless temporary 'ac' KVM: MMU: Avoid access/dirty update loop if all is well KVM: MMU: Eliminate eperm temporary KVM: MMU: Optimize is_last_gpte() KVM: MMU: Simplify walk_addr_generic() loop KVM: MMU: Optimize pte permission checks KVM: MMU: Update accessed and dirty bits after guest pagetable walk KVM: MMU: Move gpte_access() out of paging_tmpl.h KVM: MMU: Optimize gpte_access() slightly KVM: MMU: Push clean gpte write protection out of gpte_access() KVM: clarify kvmclock documentation KVM: make processes waiting on vcpu mutex killable KVM: SVM: Make use of asm.h KVM: VMX: Make use of asm.h KVM: VMX: Make lto-friendly KVM: x86: lapic: Clean up find_highest_vector() and count_vectors() ... Conflicts: arch/s390/include/asm/processor.h arch/x86/kvm/i8259.c
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+Linux KVM Hypercall:
+===================
+X86:
+ KVM Hypercalls have a three-byte sequence of either the vmcall or the vmmcall
+ instruction. The hypervisor can replace it with instructions that are
+ guaranteed to be supported.
+
+ Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively.
+ The hypercall number should be placed in rax and the return value will be
+ placed in rax. No other registers will be clobbered unless explicitly stated
+ by the particular hypercall.
+
+S390:
+ R2-R7 are used for parameters 1-6. In addition, R1 is used for hypercall
+ number. The return value is written to R2.
+
+ S390 uses diagnose instruction as hypercall (0x500) along with hypercall
+ number in R1.
+
+ PowerPC:
+ It uses R3-R10 and hypercall number in R11. R4-R11 are used as output registers.
+ Return value is placed in R3.
+
+ KVM hypercalls uses 4 byte opcode, that are patched with 'hypercall-instructions'
+ property inside the device tree's /hypervisor node.
+ For more information refer to Documentation/virtual/kvm/ppc-pv.txt
+
+KVM Hypercalls Documentation
+===========================
+The template for each hypercall is:
+1. Hypercall name.
+2. Architecture(s)
+3. Status (deprecated, obsolete, active)
+4. Purpose
+
+1. KVM_HC_VAPIC_POLL_IRQ
+------------------------
+Architecture: x86
+Status: active
+Purpose: Trigger guest exit so that the host can check for pending
+interrupts on reentry.
+
+2. KVM_HC_MMU_OP
+------------------------
+Architecture: x86
+Status: deprecated.
+Purpose: Support MMU operations such as writing to PTE,
+flushing TLB, release PT.
+
+3. KVM_HC_FEATURES
+------------------------
+Architecture: PPC
+Status: active
+Purpose: Expose hypercall availability to the guest. On x86 platforms, cpuid
+used to enumerate which hypercalls are available. On PPC, either device tree
+based lookup ( which is also what EPAPR dictates) OR KVM specific enumeration
+mechanism (which is this hypercall) can be used.
+
+4. KVM_HC_PPC_MAP_MAGIC_PAGE
+------------------------
+Architecture: PPC
+Status: active
+Purpose: To enable communication between the hypervisor and guest there is a
+shared page that contains parts of supervisor visible register state.
+The guest can map this shared page to access its supervisor register through
+memory using this hypercall.
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