| Message ID | 1443538145-11990-5-git-send-email-christoffer.dall@linaro.org |
|---|---|
| State | New |
| Headers | show |
Hi Christoffer, On 29/09/15 15:49, Christoffer Dall wrote: > The GICD_ICFGR allows the bits for the SGIs and PPIs to be read only. > We currently simulate this behavior by writing a hardcoded value to the > register for the SGIs and PPIs on every write of these bits to the > register (ignoring what the guest actually wrote), and by writing the > same value as the reset value to the register. > > This is a bit counter-intuitive, as the register is RO for these bits, > and we can just implement it that way, allowing us to control the value > of the bits purely in the reset code. > > Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> > Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> > --- > virt/kvm/arm/vgic.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c > index fe0e5db..e606f78 100644 > --- a/virt/kvm/arm/vgic.c > +++ b/virt/kvm/arm/vgic.c > @@ -655,7 +655,7 @@ bool vgic_handle_cfg_reg(u32 *reg, struct kvm_exit_mmio *mmio, > ACCESS_READ_VALUE | ACCESS_WRITE_VALUE); > if (mmio->is_write) { > if (offset < 8) { > - *reg = ~0U; /* Force PPIs/SGIs to 1 */ > + /* Ignore writes to read-only SGI and PPI bits */ > return false; > } Nit: Isn't this now violating kernel coding style because of a single statement not needing braces? Maybe move the comment in front of the if-statement to make this more obvious? Other than that: Reviewed-by: Andre Przywara <andre.przywara@arm.com> Cheers, Andre.
On Fri, Oct 02, 2015 at 03:51:50PM +0100, Andre Przywara wrote: > Hi Christoffer, > > On 29/09/15 15:49, Christoffer Dall wrote: > > The GICD_ICFGR allows the bits for the SGIs and PPIs to be read only. > > We currently simulate this behavior by writing a hardcoded value to the > > register for the SGIs and PPIs on every write of these bits to the > > register (ignoring what the guest actually wrote), and by writing the > > same value as the reset value to the register. > > > > This is a bit counter-intuitive, as the register is RO for these bits, > > and we can just implement it that way, allowing us to control the value > > of the bits purely in the reset code. > > > > Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> > > Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> > > --- > > virt/kvm/arm/vgic.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c > > index fe0e5db..e606f78 100644 > > --- a/virt/kvm/arm/vgic.c > > +++ b/virt/kvm/arm/vgic.c > > @@ -655,7 +655,7 @@ bool vgic_handle_cfg_reg(u32 *reg, struct kvm_exit_mmio *mmio, > > ACCESS_READ_VALUE | ACCESS_WRITE_VALUE); > > if (mmio->is_write) { > > if (offset < 8) { > > - *reg = ~0U; /* Force PPIs/SGIs to 1 */ > > + /* Ignore writes to read-only SGI and PPI bits */ > > return false; > > } > > Nit: Isn't this now violating kernel coding style because of a single > statement not needing braces? Maybe move the comment in front of the > if-statement to make this more obvious? > sure > Other than that: > > Reviewed-by: Andre Przywara <andre.przywara@arm.com> > Thanks, -Christoffer
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c index fe0e5db..e606f78 100644 --- a/virt/kvm/arm/vgic.c +++ b/virt/kvm/arm/vgic.c @@ -655,7 +655,7 @@ bool vgic_handle_cfg_reg(u32 *reg, struct kvm_exit_mmio *mmio, ACCESS_READ_VALUE | ACCESS_WRITE_VALUE); if (mmio->is_write) { if (offset < 8) { - *reg = ~0U; /* Force PPIs/SGIs to 1 */ + /* Ignore writes to read-only SGI and PPI bits */ return false; }