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vmm: Allow simultaneously set serial and console as TTY mode

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Cloud Hypovrisor supports legacy serial device and virito console device
for VMs. Using legacy serial device, CH can capture full VM console logs,
but its implementation is based on KVM PIO emulation and has poor
performance. Using the virtio console device, the VM console logs will
be sent to CH through the virtio ring, the performance is better, but CH
will only capture the VM console logs after the virtio console device is
initialized, the VM early startup logs will be discarded.

This patch provides a way to enable both the legacy serial device and the
virtio console device as a TTY mode by setting the leagcy serial port as
the VM's early printk device and setting the virtio console as the VM's
main console device.

Then CH can capture early boot logs from the legacy serial device and
capture later logs from the virito console device with better performance.

Signed-off-by: Yong He <alexyonghe@tencent.com>
This commit is contained in:
Yong He 2023-09-15 14:28:12 +08:00 committed by Bo Chen
parent f5899d15f6
commit bb38e4e599
1 changed files with 11 additions and 8 deletions
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19
vmm/src/config.rs
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@ -106,8 +106,6 @@ pub enum Error {
#[derive(Debug, PartialEq, Eq, Error)]
pub enum ValidationError {
/// Both console and serial are tty.
DoubleTtyMode,
/// No kernel specified
KernelMissing,
/// Missing file value for console
@ -189,7 +187,6 @@ impl fmt::Display for ValidationError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use self::ValidationError::*;
match self {
DoubleTtyMode => write!(f, "Console mode tty specified for both serial and console"),
KernelMissing => write!(f, "No kernel specified"),
ConsoleFileMissing => write!(f, "Path missing when using file console mode"),
ConsoleSocketPathMissing => write!(f, "Path missing when using socket console mode"),
@ -1930,9 +1927,18 @@ impl VmConfig {
}
}
// The 'conflict' check is introduced in commit 24438e0390d3
// (vm-virtio: Enable the vmm support for virtio-console).
//
// Allow simultaneously set serial and console as TTY mode, for
// someone want to use virtio console for better performance, and
// want to keep legacy serial to catch boot stage logs for debug.
// Using such double tty mode, you need to configure the kernel
// properly, such as:
// "console=hvc0 earlyprintk=ttyS0"
if self.console.mode == ConsoleOutputMode::Tty && self.serial.mode == ConsoleOutputMode::Tty
{
return Err(ValidationError::DoubleTtyMode);
warn!("Using TTY output for both virtio-console and serial port");
}
if self.console.mode == ConsoleOutputMode::File && self.console.file.is_none() {
@ -3110,10 +3116,7 @@ mod tests {
let mut invalid_config = valid_config.clone();
invalid_config.serial.mode = ConsoleOutputMode::Tty;
invalid_config.console.mode = ConsoleOutputMode::Tty;
assert_eq!(
invalid_config.validate(),
Err(ValidationError::DoubleTtyMode)
);
assert!(valid_config.validate().is_ok());
let mut invalid_config = valid_config.clone();
invalid_config.payload = None;