| Message ID | 20240219185809.286724-3-oliver.upton@linux.dev (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | irqchip/gic-v3-its: Fix GICv4.1 initialization after kexec | expand |
On Mon, 19 Feb 2024 18:58:07 +0000, Oliver Upton <oliver.upton@linux.dev> wrote: > > Burying the GICv4 redistributor initialization into the routine for LPIs > is a bit confusing, and can lead to sillies where unexpected codepaths > may not fully initialize the RD. > > Hoist it out of its_cpu_init_lpis() into a dedicated function. > > Signed-off-by: Oliver Upton <oliver.upton@linux.dev> > --- > drivers/irqchip/irq-gic-v3-its.c | 32 +++++++++++++++++++++----------- > 1 file changed, 21 insertions(+), 11 deletions(-) > > diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c > index 0022852ce494..63d1743f08cc 100644 > --- a/drivers/irqchip/irq-gic-v3-its.c > +++ b/drivers/irqchip/irq-gic-v3-its.c > @@ -3173,8 +3173,25 @@ static void its_cpu_init_lpis(void) > writel_relaxed(val, rbase + GICR_CTLR); > > out: > - if (gic_rdists->has_vlpis && !gic_rdists->has_rvpeid) { > + /* Make sure the GIC has seen the above */ > + dsb(sy); So having hoisted the dsb() here... > + gic_data_rdist()->flags |= RD_LOCAL_LPI_ENABLED; > + pr_info("GICv3: CPU%d: using %s LPI pending table @%pa\n", > + smp_processor_id(), > + gic_data_rdist()->flags & RD_LOCAL_PENDTABLE_PREALLOCATED ? > + "reserved" : "allocated", > + &paddr); > +} > + > +static void its_cpu_init_vlpis(void) > +{ > + /* No vLPIs? No problem. */ > + if (!gic_rdists->has_vlpis) > + return; > + > + if (!gic_rdists->has_rvpeid) { > void __iomem *vlpi_base = gic_data_rdist_vlpi_base(); > + u64 val; > > /* > * It's possible for CPU to receive VLPIs before it is > @@ -3193,7 +3210,8 @@ static void its_cpu_init_lpis(void) > * ancient programming gets left in and has possibility of > * corrupting memory. > */ > - val = its_clear_vpend_valid(vlpi_base, 0, 0); > + its_clear_vpend_valid(vlpi_base, 0, 0); > + return; I'm not sure about the necessity of this return statement. allocate_vpe_l1_table() checks for rvpeid already, so it should be fine to carry on. > } > > if (allocate_vpe_l1_table()) { > @@ -3205,15 +3223,6 @@ static void its_cpu_init_lpis(void) > gic_rdists->has_rvpeid = false; > gic_rdists->has_vlpis = false; > } > - > - /* Make sure the GIC has seen the above */ > - dsb(sy); ... we're now missing a dsb affecting the VPE table programming, as we expect things to take effect immediately. > - gic_data_rdist()->flags |= RD_LOCAL_LPI_ENABLED; > - pr_info("GICv3: CPU%d: using %s LPI pending table @%pa\n", > - smp_processor_id(), > - gic_data_rdist()->flags & RD_LOCAL_PENDTABLE_PREALLOCATED ? > - "reserved" : "allocated", > - &paddr); > } > > static void its_cpu_init_collection(struct its_node *its) > @@ -5265,6 +5274,7 @@ int its_cpu_init(void) > return ret; > > its_cpu_init_lpis(); > + its_cpu_init_vlpis(); > its_cpu_init_collections(); > } > I'm otherwise OK with the idea of splitting things up. Thanks, M.
On Sat, Feb 24, 2024 at 10:30:04AM +0000, Marc Zyngier wrote: > On Mon, 19 Feb 2024 18:58:07 +0000, Oliver Upton <oliver.upton@linux.dev> wrote: > > @@ -3193,7 +3210,8 @@ static void its_cpu_init_lpis(void) > > * ancient programming gets left in and has possibility of > > * corrupting memory. > > */ > > - val = its_clear_vpend_valid(vlpi_base, 0, 0); > > + its_clear_vpend_valid(vlpi_base, 0, 0); > > + return; > > I'm not sure about the necessity of this return statement. > allocate_vpe_l1_table() checks for rvpeid already, so it should be > fine to carry on. Yup, definitely not necessary. My aim was to have the control flow make it a bit more obvious to the reader what's going on. Having what reads as an allocation helper do a feature check isn't entirely obvious. I have no opinion either way though. > > } > > > > if (allocate_vpe_l1_table()) { > > @@ -3205,15 +3223,6 @@ static void its_cpu_init_lpis(void) > > gic_rdists->has_rvpeid = false; > > gic_rdists->has_vlpis = false; > > } > > - > > - /* Make sure the GIC has seen the above */ > > - dsb(sy); > > ... we're now missing a dsb affecting the VPE table programming, as we > expect things to take effect immediately. LOL, and on the back of a bugfix no less. I'll fix this.
On Sat, 24 Feb 2024 11:02:40 +0000, Oliver Upton <oliver.upton@linux.dev> wrote: > > On Sat, Feb 24, 2024 at 10:30:04AM +0000, Marc Zyngier wrote: > > On Mon, 19 Feb 2024 18:58:07 +0000, Oliver Upton <oliver.upton@linux.dev> wrote: > > > @@ -3193,7 +3210,8 @@ static void its_cpu_init_lpis(void) > > > * ancient programming gets left in and has possibility of > > > * corrupting memory. > > > */ > > > - val = its_clear_vpend_valid(vlpi_base, 0, 0); > > > + its_clear_vpend_valid(vlpi_base, 0, 0); > > > + return; > > > > I'm not sure about the necessity of this return statement. > > allocate_vpe_l1_table() checks for rvpeid already, so it should be > > fine to carry on. > > Yup, definitely not necessary. My aim was to have the control flow make > it a bit more obvious to the reader what's going on. > > Having what reads as an allocation helper do a feature check isn't > entirely obvious. > > I have no opinion either way though. You could move the if (allocate_vpe_l1_table()) as an 'else' branch, as the two are mutually exclusive. Thanks, M.
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index 0022852ce494..63d1743f08cc 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -3173,8 +3173,25 @@ static void its_cpu_init_lpis(void) writel_relaxed(val, rbase + GICR_CTLR); out: - if (gic_rdists->has_vlpis && !gic_rdists->has_rvpeid) { + /* Make sure the GIC has seen the above */ + dsb(sy); + gic_data_rdist()->flags |= RD_LOCAL_LPI_ENABLED; + pr_info("GICv3: CPU%d: using %s LPI pending table @%pa\n", + smp_processor_id(), + gic_data_rdist()->flags & RD_LOCAL_PENDTABLE_PREALLOCATED ? + "reserved" : "allocated", + &paddr); +} + +static void its_cpu_init_vlpis(void) +{ + /* No vLPIs? No problem. */ + if (!gic_rdists->has_vlpis) + return; + + if (!gic_rdists->has_rvpeid) { void __iomem *vlpi_base = gic_data_rdist_vlpi_base(); + u64 val; /* * It's possible for CPU to receive VLPIs before it is @@ -3193,7 +3210,8 @@ static void its_cpu_init_lpis(void) * ancient programming gets left in and has possibility of * corrupting memory. */ - val = its_clear_vpend_valid(vlpi_base, 0, 0); + its_clear_vpend_valid(vlpi_base, 0, 0); + return; } if (allocate_vpe_l1_table()) { @@ -3205,15 +3223,6 @@ static void its_cpu_init_lpis(void) gic_rdists->has_rvpeid = false; gic_rdists->has_vlpis = false; } - - /* Make sure the GIC has seen the above */ - dsb(sy); - gic_data_rdist()->flags |= RD_LOCAL_LPI_ENABLED; - pr_info("GICv3: CPU%d: using %s LPI pending table @%pa\n", - smp_processor_id(), - gic_data_rdist()->flags & RD_LOCAL_PENDTABLE_PREALLOCATED ? - "reserved" : "allocated", - &paddr); } static void its_cpu_init_collection(struct its_node *its) @@ -5265,6 +5274,7 @@ int its_cpu_init(void) return ret; its_cpu_init_lpis(); + its_cpu_init_vlpis(); its_cpu_init_collections(); }
Burying the GICv4 redistributor initialization into the routine for LPIs is a bit confusing, and can lead to sillies where unexpected codepaths may not fully initialize the RD. Hoist it out of its_cpu_init_lpis() into a dedicated function. Signed-off-by: Oliver Upton <oliver.upton@linux.dev> --- drivers/irqchip/irq-gic-v3-its.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-)