On Tue, 04 Mar 2025 16:55:50 +0000,
Fuad Tabba <tabba@xxxxxxxxxx> wrote:
>
> Hi Marc,
>
> On Mon, 10 Feb 2025 at 18:42, Marc Zyngier <maz@xxxxxxxxxx> wrote:
> >
> > In the process of decoupling KVM's view of the FGT bits from the
> > wider architectural state, use KVM's own FGT tables to build
> > a synthitic view of what is actually known.
>
> synthitic -> synthetic
Ah, I missed that one earlier. Will fix.
>
>
> > This allows for some checking along the way.
> >
> > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> > ---
> > arch/arm64/include/asm/kvm_arm.h | 4 ++
> > arch/arm64/include/asm/kvm_host.h | 14 ++++
> > arch/arm64/kvm/emulate-nested.c | 102 ++++++++++++++++++++++++++++++
> > 3 files changed, 120 insertions(+)
> >
> > diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
> > index 8d94a6c0ed5c4..e424085f2aaca 100644
> > --- a/arch/arm64/include/asm/kvm_arm.h
> > +++ b/arch/arm64/include/asm/kvm_arm.h
> > @@ -359,6 +359,10 @@
> > #define __HAFGRTR_EL2_MASK (GENMASK(49, 17) | GENMASK(4, 0))
> > #define __HAFGRTR_EL2_nMASK ~(__HAFGRTR_EL2_RES0 | __HAFGRTR_EL2_MASK)
> >
> > +/* Because the sysreg file mixes R and W... */
> > +#define HFGRTR_EL2_RES0 HFGxTR_EL2_RES0 (0)
> > +#define HFGWTR_EL2_RES0 (HFGRTR_EL2_RES0 | __HFGRTR_ONLY_MASK)
>
> __HFGRTR_ONLY_MASK is a hand-crafted bitmask. The only bit remaining
> in HFGxTR_EL2 that is RES0 is bit 51. If that were to be used as an
> HFGRTR-only bit without __HFGRTR_ONLY_MASK getting updated, then
> aggregate_fgt() below would set its bit in hfgwtr_masks. Could this be
> a problem if this happens and the polarity of this bit ends up being
> negative, thereby setting the corresponding nmask bit?
So I ended up doing exactly what I threatened to do, which is to
completely get rid of the HFGxTR nonsense, and bring HFG{R,W}TR to
their full glory.
The diffstat is a bit annoying:
arch/arm64/include/asm/el2_setup.h | 14 +--
arch/arm64/include/asm/kvm_arm.h | 4 +-
arch/arm64/include/asm/kvm_host.h | 3 +-
arch/arm64/kvm/emulate-nested.c | 154 ++++++++++++-------------
arch/arm64/kvm/hyp/include/hyp/switch.h | 4 +-
arch/arm64/kvm/hyp/vgic-v3-sr.c | 8 +-
arch/arm64/kvm/nested.c | 42 +++----
arch/arm64/kvm/sys_regs.c | 20 ++--
arch/arm64/tools/sysreg | 194 ++++++++++++++++++++------------
9 files changed, 250 insertions(+), 193 deletions(-)
but at least it puts all registers in the same bucket, and we don't
assume anything anymore.
I'll repost the series on Monday, once I'm on holiday.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
