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hv: Add IO request completion polling feature

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This patch introduce a new mode of IO request completion, polling mode.

Now, the sketch of ioreq process can be,
  A. UOS vcpu0 generate PIO/MMIO ->
   B. pcpu1(vcpu0 of UOS) trap into HV ->
    C. pcpu1 build ioreq, send IPI and enter idle ->
     D.1 pcpu0(vcpu0 of SOS) response IPI,
     D.2 pcpu0 handle the ioreq in HV, kernel, DM,
     D.3 pcpu0 mark ioreq as complete,
     D.4 pcpu0 hypercall to enter HV ->
       E.1 pcpu0 send IPI to wake pcpu1 up
       E.2 UOS vcpu0 continue running

With this change, it skips D.4, E.1 steps. In step C, pcpu1 will enter a
polling ioreq state idle after send out the IPI.
It can save about ~5000 cpu cycles.

In polling mode, we do the polling in idle instead of pause cpu all the
time. It will consume more power. A better way is to use monitor/mwait
instructions which can put cpu into a sleep state with monitoring a
memory address. Unfortunately, APL has bug with monitor. We can gather
all ioreqs state into one monitorable memory and take advantage of
monitor/mwait for future platform.

The way polling or notification is per VM. We can config VMs in
different mode. By default, IO request completion will use notification
mode for all VMs. We can switch it by Kconfig.

Tracked-On: #1821
Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
Reviewed-by: Eddie Dong <eddie.dong@intel.com>
Acked-by: Anthony Xu <anthony.xu@intel.com>
This commit is contained in:
Shuo Liu
2018-10-11 14:10:30 +08:00
committed by lijinxia
parent e350abe40d
commit e8296dce05
8 changed files with 103 additions and 4 deletions
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2
hypervisor/include/arch/x86/guest/vm.h
View File

@@ -55,6 +55,8 @@ struct vm_sw_info {
struct sw_linux linux_info;
/* HVA to IO shared page */
void *io_shared_page;
/* If enable IO completion polling mode */
bool is_completion_polling;
};
struct vm_pm_info {

9
hypervisor/include/arch/x86/ioreq.h
View File

@@ -296,6 +296,15 @@ int32_t acrn_insert_request_wait(struct acrn_vcpu *vcpu, const struct io_request
*/
void reset_vm_ioreqs(struct acrn_vm *vm);
/**
* @brief Handle completed ioreq if any one pending
*
* @param pcpu_id The physical cpu id of vcpu whose IO request to be checked
*
* @return N/A
*/
void handle_complete_ioreq(uint16_t pcpu_id);
/**
* @}
*/