Commit df01f0a1 authored by Xiaoyao Li's avatar Xiaoyao Li Committed by Sean Christopherson
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KVM: x86: Improve documentation of MSR_KVM_ASYNC_PF_EN 



Fix some incorrect statement of MSR_KVM_ASYNC_PF_EN documentation and
state clearly the token in 'struct kvm_vcpu_pv_apf_data' of 'page ready'
event is matchted with the token in CR2 in 'page not present' event.

Signed-off-by: default avatarXiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20231025055914.1201792-3-xiaoyao.li@intel.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent ccb2280e

Documentation/virt/kvm/x86/msr.rst

+9 −9
Original line number Diff line number Diff line
@@ -193,8 +193,8 @@ data: 
	Asynchronous page fault (APF) control MSR.



	Bits 63-6 hold 64-byte aligned physical address of a 64 byte memory area

	which must be in guest RAM and must be zeroed. This memory is expected

	to hold a copy of the following structure::

	which must be in guest RAM. This memory is expected to hold the

	following structure::



	  struct kvm_vcpu_pv_apf_data {

		/* Used for 'page not present' events delivered via #PF */
@@ -231,14 +231,14 @@ data: 
	as regular page fault, guest must reset 'flags' to '0' before it does

	something that can generate normal page fault.



	Bytes 5-7 of 64 byte memory location ('token') will be written to by the

	Bytes 4-7 of 64 byte memory location ('token') will be written to by the

	hypervisor at the time of APF 'page ready' event injection. The content

	of these bytes is a token which was previously delivered as 'page not

	present' event. The event indicates the page in now available. Guest is

	supposed to write '0' to 'token' when it is done handling 'page ready'

	event and to write 1' to MSR_KVM_ASYNC_PF_ACK after clearing the location;

	writing to the MSR forces KVM to re-scan its queue and deliver the next

	pending notification.

	of these bytes is a token which was previously delivered in CR2 as

	'page not present' event. The event indicates the page is now available.

	Guest is supposed to write '0' to 'token' when it is done handling

	'page ready' event and to write '1' to MSR_KVM_ASYNC_PF_ACK after

	clearing the location; writing to the MSR forces KVM to re-scan its

	queue and deliver the next pending notification.



	Note, MSR_KVM_ASYNC_PF_INT MSR specifying the interrupt vector for 'page

	ready' APF delivery needs to be written to before enabling APF mechanism