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hv:remove accessing shared log buffer cases between stac/clac 

Shared buffer is allocated by VM and is protected by SMAP.
Accessing to shared buffer between stac/clac pair will invalidate
SMAP protection.This patch is to remove these cases.
Fix minor stac/clac mis-usage,and add comments as stac/clac usage BKM

Tracked-On: #2526
Signed-off-by: Yonghua Huang <yonghua.huang@intel.com>
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
This commit is contained in:
Yonghua Huang 2019-04-30 21:28:36 +08:00 committed by wenlingz
parent 321ad5c374
commit be2fe2a44d
5 changed files with 17 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
hypervisor/arch/x86/guest/ept.c
View File

@ -49,11 +49,8 @@ uint64_t local_gpa2hpa(struct acrn_vm *vm, uint64_t gpa, uint32_t *size)
if (pgentry != NULL) {
hpa = ((*pgentry & (~(pg_size - 1UL)))
| (gpa & (pg_size - 1UL)));
pr_dbg("GPA2HPA: 0x%llx->0x%llx", gpa, hpa);
} else {
pr_err("VM %d GPA2HPA: failed for gpa 0x%llx",
vm->vm_id, gpa);
}
/**
* If specified parameter size is not NULL and
* the HPA of parameter gpa is found, pg_size shall

1
hypervisor/arch/x86/seed/seed_sbl.c
View File

@ -94,7 +94,6 @@ bool parse_seed_sbl(uint64_t addr, struct physical_seed *phy_seed)
*/
if ((entry->index != dseed_index) ||
(entry->index >= BOOTLOADER_SEED_MAX_ENTRIES)) {
pr_warn("%s: Invalid seed index.", __func__);
status = false;
break;
}

1
hypervisor/common/hypercall.c
View File

@ -1177,7 +1177,6 @@ int32_t hcall_vm_intr_monitor(struct acrn_vm *vm, uint16_t vmid, uint64_t param)
}
status = 0;
pr_dbg("intr monitor:%d, cnt=%d", intr_hdr->cmd, intr_hdr->buf_cnt);
}
clac();
}

4
hypervisor/debug/profiling.c
View File

@ -247,17 +247,15 @@ static int32_t profiling_sbuf_put_variable(struct shared_buf *sbuf,
* 5. return number of bytes of data put in buffer
*/
stac();
if ((sbuf == NULL) || (data == NULL)) {
clac();
return -EINVAL;
}
if (size == 0U) {
clac();
return 0;
}
stac();
if (sbuf->tail >= sbuf->head) {
remaining_space = sbuf->size - (sbuf->tail - sbuf->head);
} else {

15
hypervisor/include/arch/x86/cpu.h
View File

@ -464,6 +464,21 @@ static inline void write_xcr(int32_t reg, uint64_t val)
asm volatile("xsetbv" : : "c" (reg), "a" ((uint32_t)val), "d" ((uint32_t)(val >> 32U)));
}
/*
* stac/clac pair is used to access guest's memory protected by SMAP,
* following below flow:
*
* stac();
* #access guest's memory.
* clac();
*
* Notes:Avoid inserting another stac/clac pair between stac and clac,
* As once clac after multiple stac will invalidate SMAP protection
* and hence Page Fault crash.
* Logging message to memory buffer will induce this case,
* please disable SMAP temporlly or don't log messages to shared
* memory buffer, if it is evitable for you for debug purpose.
*/
static inline void stac(void)
{
asm volatile ("stac" : : : "memory");