On Wed, Mar 16, 2022 at 04:57:39PM +0100, Peter Krempa wrote: > On Tue, Mar 08, 2022 at 12:34:38 +0100, Paolo Bonzini wrote: > > From: Yang Zhong <yang.zh...@intel.com> > > > > Kernel allocates 4K xstate buffer by default. For XSAVE features > > which require large state component (e.g. AMX), Linux kernel > > dynamically expands the xstate buffer only after the process has > > acquired the necessary permissions. Those are called dynamically- > > enabled XSAVE features (or dynamic xfeatures). > > > > There are separate permissions for native tasks and guests. > > > > Qemu should request the guest permissions for dynamic xfeatures > > which will be exposed to the guest. This only needs to be done > > once before the first vcpu is created. > > > > KVM implemented one new ARCH_GET_XCOMP_SUPP system attribute API to > > get host side supported_xcr0 and Qemu can decide if it can request > > dynamically enabled XSAVE features permission. > > https://lore.kernel.org/all/20220126152210.3044876-1-pbonz...@redhat.com/ > > > > Suggested-by: Paolo Bonzini <pbonz...@redhat.com> > > Signed-off-by: Yang Zhong <yang.zh...@intel.com> > > Signed-off-by: Jing Liu <jing2....@intel.com> > > Message-Id: <20220217060434.52460-4-yang.zh...@intel.com> > > Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> > > --- > > target/i386/cpu.c | 7 +++++ > > target/i386/cpu.h | 4 +++ > > target/i386/kvm/kvm-cpu.c | 12 ++++---- > > target/i386/kvm/kvm.c | 57 ++++++++++++++++++++++++++++++++++++++ > > target/i386/kvm/kvm_i386.h | 1 + > > 5 files changed, 75 insertions(+), 6 deletions(-) > > With this commit qemu crashes for me when invoking the following > QMP command:
It is way worse than that even. If you remove '-S' you get an immediate kaboom on startup on AMD hosts $ ./build/qemu-system-x86_64 -accel kvm Unable to init server: Could not connect: Connection refused qemu-system-x86_64: ../target/i386/kvm/kvm-cpu.c:105: kvm_cpu_xsave_init: Assertion `esa->size == eax' failed. Aborted (core dumped) With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
