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arch: x86_64: Use host cpuid information for L2 cache for older KVM

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If the KVM version is too old (pre Linux 5.7) then fetch the CPUID
information from the host and use that in the guest. We prefer the KVM
version over the host version as that would use the CPUID for the
running CPU vs the CPU that runs this code which might be different due
to a hybrid topology.

Fixes: #4918

Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This commit is contained in:
Rob Bradford 2022-11-21 13:07:11 +00:00 committed by Sebastien Boeuf
parent 1c25d71127
commit 7c3110e6d5
1 changed files with 14 additions and 0 deletions
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14
arch/src/x86_64/mod.rs
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@ -633,6 +633,20 @@ pub fn generate_common_cpuid(
}
}
}
// Copy host L2 cache details if not populated by KVM
0x8000_0006 => {
if entry.eax == 0 && entry.ebx == 0 && entry.ecx == 0 && entry.edx == 0 {
// SAFETY: cpuid called with valid leaves
if unsafe { std::arch::x86_64::__cpuid(0x8000_0000).eax } >= 0x8000_0006 {
// SAFETY: cpuid called with valid leaves
let leaf = unsafe { std::arch::x86_64::__cpuid(0x8000_0006) };
entry.eax = leaf.eax;
entry.ebx = leaf.ebx;
entry.ecx = leaf.ecx;
entry.edx = leaf.edx;
}
}
}
// Set CPU physical bits
0x8000_0008 => {
entry.eax = (entry.eax & 0xffff_ff00) | (phys_bits as u32 & 0xff);