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hv: io_req: refine vhm_req status setting

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In spite of vhm_req status could be updated in HV and DM on different CPUs, they
only change vhm_req status when they detect vhm_req status has been updated by
each other. So vhm_req status will not been misconfigured. However, before HV
sets vhm_req status to REQ_STATE_PENDING, vhm_req buffer filling should be visible
to DM. Add a write memory barrier to guarantee this.

Tracked-On: #1842
Signed-off-by: Li, Fei1 <fei1.li@intel.com>
This commit is contained in:
Li, Fei1 2019-07-03 00:21:43 +08:00 committed by wenlingz
parent 1ea3052f80
commit 5930e96d12
2 changed files with 23 additions and 4 deletions
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21
hypervisor/dm/io_req.c
View File

@ -6,7 +6,6 @@
#include <vm.h> #include <vm.h>
#include <irq.h> #include <irq.h>
#include <errno.h> #include <errno.h>
#include <atomic.h>
#include <ept.h> #include <ept.h>
#include <logmsg.h> #include <logmsg.h>
@ -113,6 +112,9 @@ int32_t acrn_insert_request(struct acrn_vcpu *vcpu, const struct io_request *io_
pause_vcpu(vcpu, VCPU_PAUSED); pause_vcpu(vcpu, VCPU_PAUSED);
} }
/* Before updating the vhm_req state, enforce all fill vhm_req operations done */
cpu_write_memory_barrier();
/* Must clear the signal before we mark req as pending /* Must clear the signal before we mark req as pending
* Once we mark it pending, VHM may process req and signal us * Once we mark it pending, VHM may process req and signal us
* before we perform upcall. * before we perform upcall.
@ -168,7 +170,7 @@ uint32_t get_vhm_req_state(struct acrn_vm *vm, uint16_t vhm_req_id)
} else { } else {
stac(); stac();
vhm_req = &req_buf->req_queue[vhm_req_id]; vhm_req = &req_buf->req_queue[vhm_req_id];
state = atomic_load32(&vhm_req->processed); state = vhm_req->processed;
clac(); clac();
} }
@ -184,7 +186,13 @@ void set_vhm_req_state(struct acrn_vm *vm, uint16_t vhm_req_id, uint32_t state)
if (req_buf != NULL) { if (req_buf != NULL) {
stac(); stac();
vhm_req = &req_buf->req_queue[vhm_req_id]; vhm_req = &req_buf->req_queue[vhm_req_id];
atomic_store32(&vhm_req->processed, state); /*
* HV will only set processed to REQ_STATE_PENDING or REQ_STATE_FREE.
* we don't need to sfence here is that even if the SOS/DM sees the previous state,
* the only side effect is that it will defer the processing of the new IOReq.
* It won't lead wrong processing.
*/
vhm_req->processed = state;
clac(); clac();
} }
} }
@ -245,7 +253,12 @@ static void complete_ioreq(struct acrn_vcpu *vcpu, struct io_request *io_req)
break; break;
} }
} }
atomic_store32(&vhm_req->processed, REQ_STATE_FREE);
/*
* Only HV will check whether processed is REQ_STATE_FREE on per-vCPU before inject a ioreq.
* Only HV will set processed to REQ_STATE_FREE when ioreq is done.
*/
vhm_req->processed = REQ_STATE_FREE;
clac(); clac();
} }

6
hypervisor/include/arch/x86/cpu.h
View File

@ -351,6 +351,12 @@ static inline void cpu_sp_write(uint64_t *stack_ptr)
asm volatile ("movq %0, %%rsp" : : "r"(rsp)); asm volatile ("movq %0, %%rsp" : : "r"(rsp));
} }
/* Synchronizes all write accesses to memory */
static inline void cpu_write_memory_barrier(void)
{
asm volatile ("sfence\n" : : : "memory");
}
/* Synchronizes all read and write accesses to/from memory */ /* Synchronizes all read and write accesses to/from memory */
static inline void cpu_memory_barrier(void) static inline void cpu_memory_barrier(void)
{ {