On Mon, 2021-01-25 at 07:29 +0100, Jiri Denemark wrote: > As explained in QEMU commit 4c257911dcc7c4189768e9651755c849ce9db4e8 > intel-pt features should never be included in the CPU models as it > was > not supported by KVM back then and even once it started to be > supported, > users have to enable it by passing pt_mode=1 parameter to kvm_intel > module. The Icelake-* CPU models with intel-pt included were added to > QEMU 3.1.0 and removed right in the following 4.0.0 release (and even > in > 3.1.1 maintenance release). > > In libvirt 6.10.0 I introduced 'removed' attribute for features > included > in our CPU model definitions which we can use to drop intel-pt from > Icelake-* CPU models. Back then I explained we can safely do so only > for > features which could never be enabled, which is not the case of > intel-pt. > > Theoretically, it could be possible to create an environment in which > QEMU would enable intel-pt without asking for it explicitly: it would > need to use a new enough kernel (not available at the time of QEMU > 3.1.0) and pt_mode KVM parameter in combination with QEMU 3.1.0 > running > a domain with q35 machine type and all that on a CPU which didn't > really > exist at that time. > > Migrating such domain to a host with newer SW stack including libvirt > with this patch applied would result in incompatible guest ABI (the > virtual CPU would lose intel-pt). However, QEMU changed its CPU > models > unconditionally and thus migration would not work even without this > patch. That said, it is safe to follow QEMU and remove the feature > from > Icelake-* CPU models in our cpu_map. > > https://bugzilla.redhat.com/show_bug.cgi?id=1853972 > > Signed-off-by: Jiri Denemark <jdenemar@xxxxxxxxxx> > --- > src/cpu_map/x86_Icelake-Client-noTSX.xml | 2 > +- > src/cpu_map/x86_Icelake-Client.xml | 2 > +- > src/cpu_map/x86_Icelake-Server-noTSX.xml | 2 > +- > src/cpu_map/x86_Icelake-Server.xml | 2 > +- > tests/cputestdata/x86_64-cpuid-Ice-Lake-Server-guest.xml | 1 > + > tests/cputestdata/x86_64-cpuid-Ice-Lake-Server-host.xml | 1 > + > .../cpu-Icelake-Server-pconfig.x86_64-3.1.0.args | 2 > +- > .../cpu-Icelake-Server-pconfig.x86_64-latest.args | 2 > +- > 8 files changed, 8 insertions(+), 6 deletions(-) > > diff --git a/src/cpu_map/x86_Icelake-Client-noTSX.xml > b/src/cpu_map/x86_Icelake-Client-noTSX.xml > index 65e648ae21..217adba4f2 100644 > --- a/src/cpu_map/x86_Icelake-Client-noTSX.xml > +++ b/src/cpu_map/x86_Icelake-Client-noTSX.xml > @@ -30,7 +30,7 @@ > <feature name='fsgsbase'/> > <feature name='fxsr'/> > <feature name='gfni'/> > - <feature name='intel-pt'/> > + <feature name='intel-pt' removed='yes'/> > <feature name='invpcid'/> > <feature name='lahf_lm'/> > <feature name='lm'/> > diff --git a/src/cpu_map/x86_Icelake-Client.xml > b/src/cpu_map/x86_Icelake-Client.xml > index 5cf32e91fa..b725227f46 100644 > --- a/src/cpu_map/x86_Icelake-Client.xml > +++ b/src/cpu_map/x86_Icelake-Client.xml > @@ -31,7 +31,7 @@ > <feature name='fxsr'/> > <feature name='gfni'/> > <feature name='hle'/> > - <feature name='intel-pt'/> > + <feature name='intel-pt' removed='yes'/> > <feature name='invpcid'/> > <feature name='lahf_lm'/> > <feature name='lm'/> > diff --git a/src/cpu_map/x86_Icelake-Server-noTSX.xml > b/src/cpu_map/x86_Icelake-Server-noTSX.xml > index 34a0f7c18c..7c9c32c977 100644 > --- a/src/cpu_map/x86_Icelake-Server-noTSX.xml > +++ b/src/cpu_map/x86_Icelake-Server-noTSX.xml > @@ -37,7 +37,7 @@ > <feature name='fsgsbase'/> > <feature name='fxsr'/> > <feature name='gfni'/> > - <feature name='intel-pt'/> > + <feature name='intel-pt' removed='yes'/> > <feature name='invpcid'/> > <feature name='la57'/> > <feature name='lahf_lm'/> > diff --git a/src/cpu_map/x86_Icelake-Server.xml > b/src/cpu_map/x86_Icelake-Server.xml > index 1ee4ea9cd4..b4685bead0 100644 > --- a/src/cpu_map/x86_Icelake-Server.xml > +++ b/src/cpu_map/x86_Icelake-Server.xml > @@ -38,7 +38,7 @@ > <feature name='fxsr'/> > <feature name='gfni'/> > <feature name='hle'/> > - <feature name='intel-pt'/> > + <feature name='intel-pt' removed='yes'/> > <feature name='invpcid'/> > <feature name='la57'/> > <feature name='lahf_lm'/> > diff --git a/tests/cputestdata/x86_64-cpuid-Ice-Lake-Server-guest.xml > b/tests/cputestdata/x86_64-cpuid-Ice-Lake-Server-guest.xml > index 3a71b28cfb..7fcd20d26d 100644 > --- a/tests/cputestdata/x86_64-cpuid-Ice-Lake-Server-guest.xml > +++ b/tests/cputestdata/x86_64-cpuid-Ice-Lake-Server-guest.xml > @@ -21,6 +21,7 @@ > <feature policy='require' name='tsc_adjust'/> > <feature policy='require' name='cmt'/> > <feature policy='require' name='avx512ifma'/> > + <feature policy='require' name='intel-pt'/> > <feature policy='require' name='sha-ni'/> > <feature policy='require' name='ospke'/> > <feature policy='require' name='rdpid'/> > diff --git a/tests/cputestdata/x86_64-cpuid-Ice-Lake-Server-host.xml > b/tests/cputestdata/x86_64-cpuid-Ice-Lake-Server-host.xml > index 1582de0422..07e8f8bc24 100644 > --- a/tests/cputestdata/x86_64-cpuid-Ice-Lake-Server-host.xml > +++ b/tests/cputestdata/x86_64-cpuid-Ice-Lake-Server-host.xml > @@ -22,6 +22,7 @@ > <feature name='tsc_adjust'/> > <feature name='cmt'/> > <feature name='avx512ifma'/> > + <feature name='intel-pt'/> > <feature name='sha-ni'/> > <feature name='ospke'/> > <feature name='rdpid'/> > diff --git a/tests/qemuxml2argvdata/cpu-Icelake-Server- > pconfig.x86_64-3.1.0.args b/tests/qemuxml2argvdata/cpu-Icelake- > Server-pconfig.x86_64-3.1.0.args > index 96d4306238..b69bfe0f0f 100644 > --- a/tests/qemuxml2argvdata/cpu-Icelake-Server-pconfig.x86_64- > 3.1.0.args > +++ b/tests/qemuxml2argvdata/cpu-Icelake-Server-pconfig.x86_64- > 3.1.0.args > @@ -13,7 +13,7 @@ QEMU_AUDIO_DRV=none \ > -object secret,id=masterKey0,format=raw,\ > file=/tmp/lib/domain--1-test/master-key.aes \ > -machine pc-i440fx-3.1,accel=kvm,usb=off,dump-guest-core=off \ > --cpu Icelake-Server,pconfig=off \ > +-cpu Icelake-Server,pconfig=off,intel-pt=off \ > -m 214 \ > -overcommit mem-lock=off \ > -smp 1,sockets=1,cores=1,threads=1 \ > diff --git a/tests/qemuxml2argvdata/cpu-Icelake-Server- > pconfig.x86_64-latest.args b/tests/qemuxml2argvdata/cpu-Icelake- > Server-pconfig.x86_64-latest.args > index a512623af6..64f223bee3 100644 > --- a/tests/qemuxml2argvdata/cpu-Icelake-Server-pconfig.x86_64- > latest.args > +++ b/tests/qemuxml2argvdata/cpu-Icelake-Server-pconfig.x86_64- > latest.args > @@ -13,7 +13,7 @@ QEMU_AUDIO_DRV=none \ > -object secret,id=masterKey0,format=raw,\ > file=/tmp/lib/domain--1-test/master-key.aes \ > -machine pc,accel=kvm,usb=off,dump-guest-core=off,memory- > backend=pc.ram \ > --cpu Icelake-Server \ > +-cpu Icelake-Server,intel-pt=off \ > -m 214 \ > -object memory-backend-ram,id=pc.ram,size=224395264 \ > -overcommit mem-lock=off \ Reviewed-by: Tim Wiederhake <twiederh@xxxxxxxxxx>
