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hv: debug: Add hv console callback to VM-exit event

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In some scenarios (e.g., nested) where lapic-pt is enabled for a vcpu
running on a pcpu hosting console timer, the hv console will be
inaccessible.

This patch adds the console callback to every VM-exit event so that the
console can still be somewhat functional under such circumstance.

Since this is VM-exit driven, the VM-exit/second can be low in certain
cases (e.g., idle or running stress workload). In extreme cases where
the guest panics/hangs, there will be no VM-exits at all.

In most cases, the shell is laggy but functional (probably enough for
debugging purpose).

Tracked-On: #6312
Signed-off-by: Yifan Liu <yifan1.liu@intel.com>
This commit is contained in:
Yifan Liu 2021-07-16 15:09:00 +08:00 committed by wenlingz
parent e235d68526
commit 69fef2e685
4 changed files with 28 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
hypervisor/arch/x86/guest/vmexit.c
View File

@ -22,6 +22,7 @@
#include <asm/guest/vcpuid.h>
#include <trace.h>
#include <asm/rtcm.h>
#include <debug/console.h>
/*
* According to "SDM APPENDIX C VMX BASIC EXIT REASONS",
@ -292,6 +293,8 @@ int32_t vmexit_handler(struct acrn_vcpu *vcpu)
}
}
console_vmexit_callback(vcpu);
return ret;
}

22
hypervisor/debug/console.c
View File

@ -172,6 +172,28 @@ void console_setup_timer(void)
}
}
/* When lapic-pt is enabled for a vcpu working on the pcpu hosting
* console timer (currently BSP), we utilize vm-exits to drive the console.
*
* Note that currently this approach will result in a laggy shell when
* the number of VM-exits/second is low (which is mostly true when lapic-pt is
* enabled).
*/
void console_vmexit_callback(struct acrn_vcpu *vcpu)
{
static uint64_t prev_tsc = 0;
uint64_t tsc;
/* console_setup_timer is called on BSP only. */
if ((pcpuid_from_vcpu(vcpu) == BSP_CPU_ID) && (is_lapic_pt_enabled(vcpu))) {
tsc = cpu_ticks();
if (tsc - prev_tsc > (TICKS_PER_MS * CONSOLE_KICK_TIMER_TIMEOUT)) {
console_timer_callback(NULL);
prev_tsc = tsc;
}
}
}
void suspend_console(void)
{
del_timer(&console_timer);

2
hypervisor/include/debug/console.h
View File

@ -8,6 +8,7 @@
#define CONSOLE_H
#include <vuart.h>
#include <asm/guest/vcpu.h>
/** Initializes the console module.
*
@ -35,6 +36,7 @@ void console_putc(const char *ch);
char console_getc(void);
void console_setup_timer(void);
void console_vmexit_callback(struct acrn_vcpu *vcpu);
void suspend_console(void);
void resume_console(void);

1
hypervisor/release/console.c
View File

@ -27,6 +27,7 @@ void suspend_console(void) {}
void resume_console(void) {}
bool handle_dbg_cmd(__unused const char *cmd, __unused int32_t len) { return false; }
void console_vmexit_callback(__unused struct acrn_vcpu *vcpu) {}
void shell_init(void) {}
void shell_kick(void) {}