External/cloud-hypervisor
1
0
Fork 0
mirror of https://github.com/cloud-hypervisor/cloud-hypervisor.git synced 2024-12-22 21:55:20 +00:00
Code Issues Packages Projects Releases Wiki Activity

vmm: cpu: Disable KVM_FEATURE_ASYNC_PF_INT in CPUID

Browse Source 
By disabling this KVM feature, we prevent the guest from using APF
(Asynchronous Page Fault) mechanism. The kernel has recently switched to
using interrupts to notify about a page being ready, but for some
reasons, this is causing unexpected behavior with Cloud Hypervisor, as
it will make the vcpu thread spin at 100%.

While investigating the issue, it's better to disable the KVM feature to
prevent 100% CPU usage in some cases.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This commit is contained in:
Sebastien Boeuf 2021-04-15 09:38:59 +02:00 committed by Rob Bradford
parent d4eaf746b5
commit b92fe648e9
1 changed files with 19 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
vmm/src/cpu.rs
View File

@ -59,6 +59,10 @@ const HYPERVISOR_ECX_BIT: u8 = 31; // Hypervisor ecx bit.
#[cfg(target_arch = "x86_64")]
const MTRR_EDX_BIT: u8 = 12; // Hypervisor ecx bit.
// KVM feature bits
#[cfg(target_arch = "x86_64")]
const KVM_FEATURE_ASYNC_PF_INT_BIT: u8 = 14;
#[cfg(feature = "acpi")]
pub const CPU_MANAGER_ACPI_SIZE: usize = 0xc;
@ -685,11 +689,23 @@ impl CpuManager {
.map_err(Error::CpuidSgx)?;
}
// Set CPU physical bits
// Update some existing CPUID
for entry in cpuid.as_mut_slice().iter_mut() {
if entry.function == 0x8000_0008 {
match entry.function {
// Set CPU physical bits
0x8000_0008 => {
entry.eax = (entry.eax & 0xffff_ff00) | (phys_bits as u32 & 0xff);
}
// Disable KVM_FEATURE_ASYNC_PF_INT
// This is required until we find out why the asynchronous page
// fault is generating unexpected behavior when using interrupt
// mechanism.
// TODO: Re-enable KVM_FEATURE_ASYNC_PF_INT (#2277)
0x4000_0001 => {
entry.eax &= !(1 << KVM_FEATURE_ASYNC_PF_INT_BIT);
}
_ => {}
}
}
// Copy CPU identification string