From: myrslint <qemu.haziness...@passinbox.com> Most Intel CPUs in current use have self-snoop. The few added lines of code also check for availability of the quirk disablement option so if some CPU does not have this feature no change of behavior will occur.
Signed-off-by: Myrsky Lintu <qemu.haziness...@passinbox.com> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2943 --- target/i386/kvm/kvm.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index 369626f8c8..1102866a89 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -16,6 +16,7 @@ #include "qapi/qapi-events-run-state.h" #include "qapi/error.h" #include "qapi/visitor.h" +#include <asm-x86/kvm.h> #include <math.h> #include <sys/ioctl.h> #include <sys/utsname.h> @@ -3367,6 +3368,21 @@ int kvm_arch_init(MachineState *ms, KVMState *s) } } + /* rationale: most x86 cpus in current use have self-snoop so honoring + * guest pat is preferrable. as well, the bochs video driver bug which + * motivated making this a default enabled quirk in kvm was fixed long ago + * */ + /* check if disabling this quirk is feasible and allowed */ + ret = kvm_check_extension(s, KVM_CAP_DISABLE_QUIRKS2); + if (ret & KVM_X86_QUIRK_IGNORE_GUEST_PAT) { + ret = kvm_vm_enable_cap(s, KVM_CAP_DISABLE_QUIRKS2, 0, \ + KVM_X86_QUIRK_IGNORE_GUEST_PAT); + if (ret < 0) { + error_report("KVM_X86_QUIRK_IGNORE_GUEST_PAT available and " + "modifiable but we failed to disable it\n"); + } + } + return 0; } -- 2.49.1
