| Message ID | 1512580189-5921-1-git-send-email-julien.thierry@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Dec 06, 2017 at 05:09:49PM +0000, Julien Thierry wrote: > When VHE is not present, KVM needs to save and restores PMSCR_EL1 when > possible. If SPE is used by the host, value of PMSCR_EL1 cannot be saved > for the guest. > If the host starts using SPE between two save+restore on the same vcpu, > restore will write the value of PMSCR_EL1 read during the first save. > > Make sure __debug_save_spe_nvhe clears the value of the saved PMSCR_EL1 > when the guest cannot use SPE. Ok, so the problem is that we have a stale (non-zero) saved pmscr_el1, and therefore the restore code unconditionally restores that even though SPE is no longer in use by the host. Well spotted! > Signed-off-by: Julien Thierry <julien.thierry@arm.com> > Cc: Christoffer Dall <christoffer.dall@linaro.org> > Cc: Marc Zyngier <marc.zyngier@arm.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > Cc: <stable@vger.kernel.org> > --- > arch/arm64/kvm/hyp/debug-sr.c | 3 +++ > 1 file changed, 3 insertions(+) Reviewed-by: Will Deacon <will.deacon@arm.com> Will
On Wed, Dec 06, 2017 at 05:09:49PM +0000, Julien Thierry wrote: > When VHE is not present, KVM needs to save and restores PMSCR_EL1 when > possible. If SPE is used by the host, value of PMSCR_EL1 cannot be saved > for the guest. > If the host starts using SPE between two save+restore on the same vcpu, > restore will write the value of PMSCR_EL1 read during the first save. > > Make sure __debug_save_spe_nvhe clears the value of the saved PMSCR_EL1 > when the guest cannot use SPE. > > Signed-off-by: Julien Thierry <julien.thierry@arm.com> > Cc: Christoffer Dall <christoffer.dall@linaro.org> > Cc: Marc Zyngier <marc.zyngier@arm.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > Cc: <stable@vger.kernel.org> > --- > arch/arm64/kvm/hyp/debug-sr.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/arm64/kvm/hyp/debug-sr.c b/arch/arm64/kvm/hyp/debug-sr.c > index 321c9c0..f4363d4 100644 > --- a/arch/arm64/kvm/hyp/debug-sr.c > +++ b/arch/arm64/kvm/hyp/debug-sr.c > @@ -74,6 +74,9 @@ static void __hyp_text __debug_save_spe_nvhe(u64 *pmscr_el1) > { > u64 reg; > > + /* Clear pmscr in case of early return */ > + *pmscr_el1 = 0; > + > /* SPE present on this CPU? */ > if (!cpuid_feature_extract_unsigned_field(read_sysreg(id_aa64dfr0_el1), > ID_AA64DFR0_PMSVER_SHIFT)) > -- > 1.9.1 Applied, thanks. -Christoffer
diff --git a/arch/arm64/kvm/hyp/debug-sr.c b/arch/arm64/kvm/hyp/debug-sr.c index 321c9c0..f4363d4 100644 --- a/arch/arm64/kvm/hyp/debug-sr.c +++ b/arch/arm64/kvm/hyp/debug-sr.c @@ -74,6 +74,9 @@ static void __hyp_text __debug_save_spe_nvhe(u64 *pmscr_el1) { u64 reg; + /* Clear pmscr in case of early return */ + *pmscr_el1 = 0; + /* SPE present on this CPU? */ if (!cpuid_feature_extract_unsigned_field(read_sysreg(id_aa64dfr0_el1), ID_AA64DFR0_PMSVER_SHIFT))
When VHE is not present, KVM needs to save and restores PMSCR_EL1 when possible. If SPE is used by the host, value of PMSCR_EL1 cannot be saved for the guest. If the host starts using SPE between two save+restore on the same vcpu, restore will write the value of PMSCR_EL1 read during the first save. Make sure __debug_save_spe_nvhe clears the value of the saved PMSCR_EL1 when the guest cannot use SPE. Signed-off-by: Julien Thierry <julien.thierry@arm.com> Cc: Christoffer Dall <christoffer.dall@linaro.org> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: <stable@vger.kernel.org> --- arch/arm64/kvm/hyp/debug-sr.c | 3 +++ 1 file changed, 3 insertions(+) -- 1.9.1