* [PATCH v2 0/2] Enhance maximum priority support of PLIC
@ 2022-09-30 12:32 Jim Shu
2022-09-30 12:32 ` [PATCH v2 1/2] hw/intc: sifive_plic: fix hard-coded max priority level Jim Shu
2022-09-30 12:32 ` [PATCH v2 2/2] hw/intc: sifive_plic: change interrupt priority register to WARL field Jim Shu
0 siblings, 2 replies; 6+ messages in thread
From: Jim Shu @ 2022-09-30 12:32 UTC (permalink / raw)
To: qemu-devel, qemu-riscv
Cc: Alistair Francis, Bin Meng, Palmer Dabbelt, chigot, Jim Shu
This patchset fixes hard-coded maximum priority of interrupt priority
register and also changes this register to WARL field to align the PLIC
spec.
Changelog:
v2:
* change interrupt priority register to WARL field.
Jim Shu (2):
hw/intc: sifive_plic: fix hard-coded max priority level
hw/intc: sifive_plic: change interrupt priority register to WARL field
hw/intc/sifive_plic.c | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)
--
2.17.1
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2 1/2] hw/intc: sifive_plic: fix hard-coded max priority level
2022-09-30 12:32 [PATCH v2 0/2] Enhance maximum priority support of PLIC Jim Shu
@ 2022-09-30 12:32 ` Jim Shu
2022-09-30 12:32 ` [PATCH v2 2/2] hw/intc: sifive_plic: change interrupt priority register to WARL field Jim Shu
1 sibling, 0 replies; 6+ messages in thread
From: Jim Shu @ 2022-09-30 12:32 UTC (permalink / raw)
To: qemu-devel, qemu-riscv
Cc: Alistair Francis, Bin Meng, Palmer Dabbelt, chigot, Jim Shu,
Emmanuel Blot
The maximum priority level is hard-coded when writing to interrupt
priority register. However, when writing to priority threshold register,
the maximum priority level is from num_priorities Property which is
configured by platform.
Also change interrupt priority register to use num_priorities Property
in maximum priority level.
Signed-off-by: Emmanuel Blot <emmanuel.blot@sifive.com>
Signed-off-by: Jim Shu <jim.shu@sifive.com>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
---
hw/intc/sifive_plic.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/hw/intc/sifive_plic.c b/hw/intc/sifive_plic.c
index af4ae3630e..f864efa761 100644
--- a/hw/intc/sifive_plic.c
+++ b/hw/intc/sifive_plic.c
@@ -180,8 +180,10 @@ static void sifive_plic_write(void *opaque, hwaddr addr, uint64_t value,
if (addr_between(addr, plic->priority_base, plic->num_sources << 2)) {
uint32_t irq = ((addr - plic->priority_base) >> 2) + 1;
- plic->source_priority[irq] = value & 7;
- sifive_plic_update(plic);
+ if (value <= plic->num_priorities) {
+ plic->source_priority[irq] = value;
+ sifive_plic_update(plic);
+ }
} else if (addr_between(addr, plic->pending_base,
plic->num_sources >> 3)) {
qemu_log_mask(LOG_GUEST_ERROR,
--
2.17.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v2 2/2] hw/intc: sifive_plic: change interrupt priority register to WARL field
2022-09-30 12:32 [PATCH v2 0/2] Enhance maximum priority support of PLIC Jim Shu
2022-09-30 12:32 ` [PATCH v2 1/2] hw/intc: sifive_plic: fix hard-coded max priority level Jim Shu
@ 2022-09-30 12:32 ` Jim Shu
2022-09-30 12:58 ` Clément Chigot
1 sibling, 1 reply; 6+ messages in thread
From: Jim Shu @ 2022-09-30 12:32 UTC (permalink / raw)
To: qemu-devel, qemu-riscv
Cc: Alistair Francis, Bin Meng, Palmer Dabbelt, chigot, Jim Shu
PLIC spec [1] requires interrupt source priority registers are WARL
field and the number of supported priority is power-of-2 to simplify SW
discovery.
Existing QEMU RISC-V machine (e.g. shakti_c) don't strictly follow PLIC
spec, whose number of supported priority is not power-of-2. Just change
each bit of interrupt priority register to WARL field when the number of
supported priority is power-of-2.
[1] https://github.com/riscv/riscv-plic-spec/blob/master/riscv-plic.adoc#interrupt-priorities
Signed-off-by: Jim Shu <jim.shu@sifive.com>
---
hw/intc/sifive_plic.c | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)
diff --git a/hw/intc/sifive_plic.c b/hw/intc/sifive_plic.c
index f864efa761..218ccff8bd 100644
--- a/hw/intc/sifive_plic.c
+++ b/hw/intc/sifive_plic.c
@@ -180,7 +180,15 @@ static void sifive_plic_write(void *opaque, hwaddr addr, uint64_t value,
if (addr_between(addr, plic->priority_base, plic->num_sources << 2)) {
uint32_t irq = ((addr - plic->priority_base) >> 2) + 1;
- if (value <= plic->num_priorities) {
+ if ((plic->num_priorities + 1) & (plic->num_priorities)) {
+ /*
+ * if "num_priorities + 1" is power-of-2, make each register bit of
+ * interrupt priority WARL (Write-Any-Read-Legal). Just filter
+ * out the access to unsupported priority bits.
+ */
+ plic->source_priority[irq] = value % (plic->num_priorities + 1);
+ sifive_plic_update(plic);
+ } else if (value <= plic->num_priorities) {
plic->source_priority[irq] = value;
sifive_plic_update(plic);
}
@@ -207,7 +215,16 @@ static void sifive_plic_write(void *opaque, hwaddr addr, uint64_t value,
uint32_t contextid = (addr & (plic->context_stride - 1));
if (contextid == 0) {
- if (value <= plic->num_priorities) {
+ if ((plic->num_priorities + 1) & (plic->num_priorities)) {
+ /*
+ * if "num_priorities + 1" is power-of-2, each register bit of
+ * interrupt priority is WARL (Write-Any-Read-Legal). Just
+ * filter out the access to unsupported priority bits.
+ */
+ plic->target_priority[addrid] = value %
+ (plic->num_priorities + 1);
+ sifive_plic_update(plic);
+ } else if (value <= plic->num_priorities) {
plic->target_priority[addrid] = value;
sifive_plic_update(plic);
}
--
2.17.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v2 2/2] hw/intc: sifive_plic: change interrupt priority register to WARL field
2022-09-30 12:32 ` [PATCH v2 2/2] hw/intc: sifive_plic: change interrupt priority register to WARL field Jim Shu
@ 2022-09-30 12:58 ` Clément Chigot
2022-09-30 13:09 ` Jim Shu
0 siblings, 1 reply; 6+ messages in thread
From: Clément Chigot @ 2022-09-30 12:58 UTC (permalink / raw)
To: Jim Shu
Cc: qemu-devel, qemu-riscv, Alistair Francis, Bin Meng, Palmer Dabbelt
Hi Jim,
On Fri, Sep 30, 2022 at 2:32 PM Jim Shu <jim.shu@sifive.com> wrote:
>
> PLIC spec [1] requires interrupt source priority registers are WARL
> field and the number of supported priority is power-of-2 to simplify SW
> discovery.
>
> Existing QEMU RISC-V machine (e.g. shakti_c) don't strictly follow PLIC
> spec, whose number of supported priority is not power-of-2. Just change
> each bit of interrupt priority register to WARL field when the number of
> supported priority is power-of-2.
>
> [1] https://github.com/riscv/riscv-plic-spec/blob/master/riscv-plic.adoc#interrupt-priorities
>
> Signed-off-by: Jim Shu <jim.shu@sifive.com>
> ---
> hw/intc/sifive_plic.c | 21 +++++++++++++++++++--
> 1 file changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/hw/intc/sifive_plic.c b/hw/intc/sifive_plic.c
> index f864efa761..218ccff8bd 100644
> --- a/hw/intc/sifive_plic.c
> +++ b/hw/intc/sifive_plic.c
> @@ -180,7 +180,15 @@ static void sifive_plic_write(void *opaque, hwaddr addr, uint64_t value,
> if (addr_between(addr, plic->priority_base, plic->num_sources << 2)) {
> uint32_t irq = ((addr - plic->priority_base) >> 2) + 1;
>
> - if (value <= plic->num_priorities) {
> + if ((plic->num_priorities + 1) & (plic->num_priorities)) {
That's the opposite. If n is a power of 2, n & (n-1) == 0 (eg 8 & 7 ==
0, 9 & 8 == 8).
Note that n must be positive too. But I'm not sure it matters here.
I'll let you decide.
> + /*
> + * if "num_priorities + 1" is power-of-2, make each register bit of
> + * interrupt priority WARL (Write-Any-Read-Legal). Just filter
> + * out the access to unsupported priority bits.
> + */
> + plic->source_priority[irq] = value % (plic->num_priorities + 1);
> + sifive_plic_update(plic);
> + } else if (value <= plic->num_priorities) {
> plic->source_priority[irq] = value;
> sifive_plic_update(plic);
> }
> @@ -207,7 +215,16 @@ static void sifive_plic_write(void *opaque, hwaddr addr, uint64_t value,
> uint32_t contextid = (addr & (plic->context_stride - 1));
>
> if (contextid == 0) {
> - if (value <= plic->num_priorities) {
> + if ((plic->num_priorities + 1) & (plic->num_priorities)) {
Same.
> + /*
> + * if "num_priorities + 1" is power-of-2, each register bit of
> + * interrupt priority is WARL (Write-Any-Read-Legal). Just
> + * filter out the access to unsupported priority bits.
> + */
> + plic->target_priority[addrid] = value %
> + (plic->num_priorities + 1);
> + sifive_plic_update(plic);
> + } else if (value <= plic->num_priorities) {
> plic->target_priority[addrid] = value;
> sifive_plic_update(plic);
> }
> --
> 2.17.1
Clément
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 2/2] hw/intc: sifive_plic: change interrupt priority register to WARL field
2022-09-30 12:58 ` Clément Chigot
@ 2022-09-30 13:09 ` Jim Shu
2022-10-03 4:13 ` Jim Shu
0 siblings, 1 reply; 6+ messages in thread
From: Jim Shu @ 2022-09-30 13:09 UTC (permalink / raw)
To: Clément Chigot
Cc: qemu-devel, qemu-riscv, Alistair Francis, Bin Meng, Palmer Dabbelt
hi Clément,
Thank you very much.
I'll fix it in the next version patch.
Thanks,
Jim Shu
On Fri, Sep 30, 2022 at 8:58 PM Clément Chigot <chigot@adacore.com> wrote:
>
> Hi Jim,
>
> On Fri, Sep 30, 2022 at 2:32 PM Jim Shu <jim.shu@sifive.com> wrote:
> >
> > PLIC spec [1] requires interrupt source priority registers are WARL
> > field and the number of supported priority is power-of-2 to simplify SW
> > discovery.
> >
> > Existing QEMU RISC-V machine (e.g. shakti_c) don't strictly follow PLIC
> > spec, whose number of supported priority is not power-of-2. Just change
> > each bit of interrupt priority register to WARL field when the number of
> > supported priority is power-of-2.
> >
> > [1] https://github.com/riscv/riscv-plic-spec/blob/master/riscv-plic.adoc#interrupt-priorities
> >
> > Signed-off-by: Jim Shu <jim.shu@sifive.com>
> > ---
> > hw/intc/sifive_plic.c | 21 +++++++++++++++++++--
> > 1 file changed, 19 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/intc/sifive_plic.c b/hw/intc/sifive_plic.c
> > index f864efa761..218ccff8bd 100644
> > --- a/hw/intc/sifive_plic.c
> > +++ b/hw/intc/sifive_plic.c
> > @@ -180,7 +180,15 @@ static void sifive_plic_write(void *opaque, hwaddr addr, uint64_t value,
> > if (addr_between(addr, plic->priority_base, plic->num_sources << 2)) {
> > uint32_t irq = ((addr - plic->priority_base) >> 2) + 1;
> >
> > - if (value <= plic->num_priorities) {
> > + if ((plic->num_priorities + 1) & (plic->num_priorities)) {
>
> That's the opposite. If n is a power of 2, n & (n-1) == 0 (eg 8 & 7 ==
> 0, 9 & 8 == 8).
> Note that n must be positive too. But I'm not sure it matters here.
> I'll let you decide.
>
> > + /*
> > + * if "num_priorities + 1" is power-of-2, make each register bit of
> > + * interrupt priority WARL (Write-Any-Read-Legal). Just filter
> > + * out the access to unsupported priority bits.
> > + */
> > + plic->source_priority[irq] = value % (plic->num_priorities + 1);
> > + sifive_plic_update(plic);
> > + } else if (value <= plic->num_priorities) {
> > plic->source_priority[irq] = value;
> > sifive_plic_update(plic);
> > }
> > @@ -207,7 +215,16 @@ static void sifive_plic_write(void *opaque, hwaddr addr, uint64_t value,
> > uint32_t contextid = (addr & (plic->context_stride - 1));
> >
> > if (contextid == 0) {
> > - if (value <= plic->num_priorities) {
> > + if ((plic->num_priorities + 1) & (plic->num_priorities)) {
>
> Same.
>
> > + /*
> > + * if "num_priorities + 1" is power-of-2, each register bit of
> > + * interrupt priority is WARL (Write-Any-Read-Legal). Just
> > + * filter out the access to unsupported priority bits.
> > + */
> > + plic->target_priority[addrid] = value %
> > + (plic->num_priorities + 1);
> > + sifive_plic_update(plic);
> > + } else if (value <= plic->num_priorities) {
> > plic->target_priority[addrid] = value;
> > sifive_plic_update(plic);
> > }
> > --
> > 2.17.1
>
> Clément
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 2/2] hw/intc: sifive_plic: change interrupt priority register to WARL field
2022-09-30 13:09 ` Jim Shu
@ 2022-10-03 4:13 ` Jim Shu
0 siblings, 0 replies; 6+ messages in thread
From: Jim Shu @ 2022-10-03 4:13 UTC (permalink / raw)
To: Clément Chigot
Cc: qemu-devel, qemu-riscv, Alistair Francis, Bin Meng, Palmer Dabbelt
Hi Clément,
> > > @@ -180,7 +180,15 @@ static void sifive_plic_write(void *opaque, hwaddr addr, uint64_t value,
> > > if (addr_between(addr, plic->priority_base, plic->num_sources << 2)) {
> > > uint32_t irq = ((addr - plic->priority_base) >> 2) + 1;
> > >
> > > - if (value <= plic->num_priorities) {
> > > + if ((plic->num_priorities + 1) & (plic->num_priorities)) {
> >
> > That's the opposite. If n is a power of 2, n & (n-1) == 0 (eg 8 & 7 ==
> > 0, 9 & 8 == 8).
> > Note that n must be positive too. But I'm not sure it matters here.
> > I'll let you decide.
> >
num_priorities is a uint32_t variable so that n is always positive.
^ permalink raw reply [flat|nested] 6+ messages in thread
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2022-09-30 12:32 ` [PATCH v2 2/2] hw/intc: sifive_plic: change interrupt priority register to WARL field Jim Shu
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