Doorbell emulation is broken for KVM on PowerVM guests as support for
DPDES was not added in the initial patch series. Due to this, a KVM on
PowerVM guest cannot be booted with the XICS interrupt controller as
doorbells are to be setup in the initial probe path when using XICS
(pSeries_smp_probe()). Add DPDES support in the host KVM code to fix
doorbell emulation.
Fixes: 6ccbbc33f06a ("KVM: PPC: Add helper library for Guest State Buffers")
Cc: [email protected]
Signed-off-by: Gautam Menghani <[email protected]>
---
v1 -> v1 resend:
1. Add the stable tag
Documentation/arch/powerpc/kvm-nested.rst | 4 +++-
arch/powerpc/include/asm/guest-state-buffer.h | 3 ++-
arch/powerpc/include/asm/kvm_book3s.h | 1 +
arch/powerpc/kvm/book3s_hv.c | 14 +++++++++++++-
arch/powerpc/kvm/book3s_hv_nestedv2.c | 7 +++++++
arch/powerpc/kvm/test-guest-state-buffer.c | 2 +-
6 files changed, 27 insertions(+), 4 deletions(-)
diff --git a/Documentation/arch/powerpc/kvm-nested.rst b/Documentation/arch/powerpc/kvm-nested.rst
index 630602a8aa00..5defd13cc6c1 100644
--- a/Documentation/arch/powerpc/kvm-nested.rst
+++ b/Documentation/arch/powerpc/kvm-nested.rst
@@ -546,7 +546,9 @@ table information.
+--------+-------+----+--------+----------------------------------+
| 0x1052 | 0x08 | RW | T | CTRL |
+--------+-------+----+--------+----------------------------------+
-| 0x1053-| | | | Reserved |
+| 0x1053 | 0x08 | RW | T | DPDES |
++--------+-------+----+--------+----------------------------------+
+| 0x1054-| | | | Reserved |
| 0x1FFF | | | | |
+--------+-------+----+--------+----------------------------------+
| 0x2000 | 0x04 | RW | T | CR |
diff --git a/arch/powerpc/include/asm/guest-state-buffer.h b/arch/powerpc/include/asm/guest-state-buffer.h
index 808149f31576..d107abe1468f 100644
--- a/arch/powerpc/include/asm/guest-state-buffer.h
+++ b/arch/powerpc/include/asm/guest-state-buffer.h
@@ -81,6 +81,7 @@
#define KVMPPC_GSID_HASHKEYR 0x1050
#define KVMPPC_GSID_HASHPKEYR 0x1051
#define KVMPPC_GSID_CTRL 0x1052
+#define KVMPPC_GSID_DPDES 0x1053
#define KVMPPC_GSID_CR 0x2000
#define KVMPPC_GSID_PIDR 0x2001
@@ -110,7 +111,7 @@
#define KVMPPC_GSE_META_COUNT (KVMPPC_GSE_META_END - KVMPPC_GSE_META_START + 1)
#define KVMPPC_GSE_DW_REGS_START KVMPPC_GSID_GPR(0)
-#define KVMPPC_GSE_DW_REGS_END KVMPPC_GSID_CTRL
+#define KVMPPC_GSE_DW_REGS_END KVMPPC_GSID_DPDES
#define KVMPPC_GSE_DW_REGS_COUNT \
(KVMPPC_GSE_DW_REGS_END - KVMPPC_GSE_DW_REGS_START + 1)
diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
index 3e1e2a698c9e..10618622d7ef 100644
--- a/arch/powerpc/include/asm/kvm_book3s.h
+++ b/arch/powerpc/include/asm/kvm_book3s.h
@@ -594,6 +594,7 @@ static inline u##size kvmppc_get_##reg(struct kvm_vcpu *vcpu) \
KVMPPC_BOOK3S_VCORE_ACCESSOR(vtb, 64, KVMPPC_GSID_VTB)
+KVMPPC_BOOK3S_VCORE_ACCESSOR(dpdes, 64, KVMPPC_GSID_DPDES)
KVMPPC_BOOK3S_VCORE_ACCESSOR_GET(arch_compat, 32, KVMPPC_GSID_LOGICAL_PVR)
KVMPPC_BOOK3S_VCORE_ACCESSOR_GET(lpcr, 64, KVMPPC_GSID_LPCR)
KVMPPC_BOOK3S_VCORE_ACCESSOR_SET(tb_offset, 64, KVMPPC_GSID_TB_OFFSET)
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 35cb014a0c51..cf285e5153ba 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4116,6 +4116,11 @@ static int kvmhv_vcpu_entry_nestedv2(struct kvm_vcpu *vcpu, u64 time_limit,
int trap;
long rc;
+ if (vcpu->arch.doorbell_request) {
+ vcpu->arch.doorbell_request = 0;
+ kvmppc_set_dpdes(vcpu, 1);
+ }
+
io = &vcpu->arch.nestedv2_io;
msr = mfmsr();
@@ -4278,9 +4283,16 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit,
if (kvmhv_on_pseries()) {
if (kvmhv_is_nestedv1())
trap = kvmhv_vcpu_entry_p9_nested(vcpu, time_limit, lpcr, tb);
- else
+ else {
trap = kvmhv_vcpu_entry_nestedv2(vcpu, time_limit, lpcr, tb);
+ /* Remember doorbell if it is pending */
+ if (kvmppc_get_dpdes(vcpu)) {
+ vcpu->arch.doorbell_request = 1;
+ kvmppc_set_dpdes(vcpu, 0);
+ }
+ }
+
/* H_CEDE has to be handled now, not later */
if (trap == BOOK3S_INTERRUPT_SYSCALL && !nested &&
kvmppc_get_gpr(vcpu, 3) == H_CEDE) {
diff --git a/arch/powerpc/kvm/book3s_hv_nestedv2.c b/arch/powerpc/kvm/book3s_hv_nestedv2.c
index 8e6f5355f08b..36863fff2a99 100644
--- a/arch/powerpc/kvm/book3s_hv_nestedv2.c
+++ b/arch/powerpc/kvm/book3s_hv_nestedv2.c
@@ -311,6 +311,10 @@ static int gs_msg_ops_vcpu_fill_info(struct kvmppc_gs_buff *gsb,
rc = kvmppc_gse_put_u64(gsb, iden,
vcpu->arch.vcore->vtb);
break;
+ case KVMPPC_GSID_DPDES:
+ rc = kvmppc_gse_put_u64(gsb, iden,
+ vcpu->arch.vcore->dpdes);
+ break;
case KVMPPC_GSID_LPCR:
rc = kvmppc_gse_put_u64(gsb, iden,
vcpu->arch.vcore->lpcr);
@@ -543,6 +547,9 @@ static int gs_msg_ops_vcpu_refresh_info(struct kvmppc_gs_msg *gsm,
case KVMPPC_GSID_VTB:
vcpu->arch.vcore->vtb = kvmppc_gse_get_u64(gse);
break;
+ case KVMPPC_GSID_DPDES:
+ vcpu->arch.vcore->dpdes = kvmppc_gse_get_u64(gse);
+ break;
case KVMPPC_GSID_LPCR:
vcpu->arch.vcore->lpcr = kvmppc_gse_get_u64(gse);
break;
diff --git a/arch/powerpc/kvm/test-guest-state-buffer.c b/arch/powerpc/kvm/test-guest-state-buffer.c
index 4720b8dc8837..91ae660cfe21 100644
--- a/arch/powerpc/kvm/test-guest-state-buffer.c
+++ b/arch/powerpc/kvm/test-guest-state-buffer.c
@@ -151,7 +151,7 @@ static void test_gs_bitmap(struct kunit *test)
i++;
}
- for (u16 iden = KVMPPC_GSID_GPR(0); iden <= KVMPPC_GSID_CTRL; iden++) {
+ for (u16 iden = KVMPPC_GSID_GPR(0); iden <= KVMPPC_GSID_DPDES; iden++) {
kvmppc_gsbm_set(&gsbm, iden);
kvmppc_gsbm_set(&gsbm1, iden);
KUNIT_EXPECT_TRUE(test, kvmppc_gsbm_test(&gsbm, iden));
--
2.45.0
On Wed May 22, 2024 at 6:49 PM AEST, Gautam Menghani wrote:
> Doorbell emulation is broken for KVM on PowerVM guests as support for
> DPDES was not added in the initial patch series. Due to this, a KVM on
> PowerVM guest cannot be booted with the XICS interrupt controller as
> doorbells are to be setup in the initial probe path when using XICS
> (pSeries_smp_probe()). Add DPDES support in the host KVM code to fix
> doorbell emulation.
This is broken when the KVM guest has SMT > 1? Or is it broken for SMT=1
as well? Can you explain a bit more of what breaks if it's the latter?
> Fixes: 6ccbbc33f06a ("KVM: PPC: Add helper library for Guest State Buffers")
> Cc: [email protected]
> Signed-off-by: Gautam Menghani <[email protected]>
> ---
> v1 -> v1 resend:
> 1. Add the stable tag
>
> Documentation/arch/powerpc/kvm-nested.rst | 4 +++-
> arch/powerpc/include/asm/guest-state-buffer.h | 3 ++-
> arch/powerpc/include/asm/kvm_book3s.h | 1 +
> arch/powerpc/kvm/book3s_hv.c | 14 +++++++++++++-
> arch/powerpc/kvm/book3s_hv_nestedv2.c | 7 +++++++
> arch/powerpc/kvm/test-guest-state-buffer.c | 2 +-
> 6 files changed, 27 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/arch/powerpc/kvm-nested.rst b/Documentation/arch/powerpc/kvm-nested.rst
> index 630602a8aa00..5defd13cc6c1 100644
> --- a/Documentation/arch/powerpc/kvm-nested.rst
> +++ b/Documentation/arch/powerpc/kvm-nested.rst
> @@ -546,7 +546,9 @@ table information.
> +--------+-------+----+--------+----------------------------------+
> | 0x1052 | 0x08 | RW | T | CTRL |
> +--------+-------+----+--------+----------------------------------+
> -| 0x1053-| | | | Reserved |
> +| 0x1053 | 0x08 | RW | T | DPDES |
> ++--------+-------+----+--------+----------------------------------+
> +| 0x1054-| | | | Reserved |
> | 0x1FFF | | | | |
> +--------+-------+----+--------+----------------------------------+
> | 0x2000 | 0x04 | RW | T | CR |
> diff --git a/arch/powerpc/include/asm/guest-state-buffer.h b/arch/powerpc/include/asm/guest-state-buffer.h
> index 808149f31576..d107abe1468f 100644
> --- a/arch/powerpc/include/asm/guest-state-buffer.h
> +++ b/arch/powerpc/include/asm/guest-state-buffer.h
> @@ -81,6 +81,7 @@
> #define KVMPPC_GSID_HASHKEYR 0x1050
> #define KVMPPC_GSID_HASHPKEYR 0x1051
> #define KVMPPC_GSID_CTRL 0x1052
> +#define KVMPPC_GSID_DPDES 0x1053
>
> #define KVMPPC_GSID_CR 0x2000
> #define KVMPPC_GSID_PIDR 0x2001
> @@ -110,7 +111,7 @@
> #define KVMPPC_GSE_META_COUNT (KVMPPC_GSE_META_END - KVMPPC_GSE_META_START + 1)
>
> #define KVMPPC_GSE_DW_REGS_START KVMPPC_GSID_GPR(0)
> -#define KVMPPC_GSE_DW_REGS_END KVMPPC_GSID_CTRL
> +#define KVMPPC_GSE_DW_REGS_END KVMPPC_GSID_DPDES
> #define KVMPPC_GSE_DW_REGS_COUNT \
> (KVMPPC_GSE_DW_REGS_END - KVMPPC_GSE_DW_REGS_START + 1)
>
> diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
> index 3e1e2a698c9e..10618622d7ef 100644
> --- a/arch/powerpc/include/asm/kvm_book3s.h
> +++ b/arch/powerpc/include/asm/kvm_book3s.h
> @@ -594,6 +594,7 @@ static inline u##size kvmppc_get_##reg(struct kvm_vcpu *vcpu) \
>
>
> KVMPPC_BOOK3S_VCORE_ACCESSOR(vtb, 64, KVMPPC_GSID_VTB)
> +KVMPPC_BOOK3S_VCORE_ACCESSOR(dpdes, 64, KVMPPC_GSID_DPDES)
> KVMPPC_BOOK3S_VCORE_ACCESSOR_GET(arch_compat, 32, KVMPPC_GSID_LOGICAL_PVR)
> KVMPPC_BOOK3S_VCORE_ACCESSOR_GET(lpcr, 64, KVMPPC_GSID_LPCR)
> KVMPPC_BOOK3S_VCORE_ACCESSOR_SET(tb_offset, 64, KVMPPC_GSID_TB_OFFSET)
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 35cb014a0c51..cf285e5153ba 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -4116,6 +4116,11 @@ static int kvmhv_vcpu_entry_nestedv2(struct kvm_vcpu *vcpu, u64 time_limit,
> int trap;
> long rc;
>
> + if (vcpu->arch.doorbell_request) {
> + vcpu->arch.doorbell_request = 0;
> + kvmppc_set_dpdes(vcpu, 1);
> + }
This probably looks okay... hmm, is the v1 KVM emulating doorbells
correctly for SMT L2 guests? I wonder if doorbell emulation isn't
broken there too because the L1 code looks to be passing in vc->dpdes
but all the POWER9 emulation code uses doorbell_request.
> +
> io = &vcpu->arch.nestedv2_io;
>
> msr = mfmsr();
> @@ -4278,9 +4283,16 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit,
> if (kvmhv_on_pseries()) {
> if (kvmhv_is_nestedv1())
> trap = kvmhv_vcpu_entry_p9_nested(vcpu, time_limit, lpcr, tb);
> - else
> + else {
> trap = kvmhv_vcpu_entry_nestedv2(vcpu, time_limit, lpcr, tb);
>
> + /* Remember doorbell if it is pending */
> + if (kvmppc_get_dpdes(vcpu)) {
> + vcpu->arch.doorbell_request = 1;
> + kvmppc_set_dpdes(vcpu, 0);
> + }
This is adding an extra get state for every entry, not good. I don't
think it's actually needed though. I don't think the L1 cares at this
stage what the L2 DPDES state is. So you sholud be able to drop this
hunk.
> + }
> +
> /* H_CEDE has to be handled now, not later */
> if (trap == BOOK3S_INTERRUPT_SYSCALL && !nested &&
> kvmppc_get_gpr(vcpu, 3) == H_CEDE) {
> diff --git a/arch/powerpc/kvm/book3s_hv_nestedv2.c b/arch/powerpc/kvm/book3s_hv_nestedv2.c
> index 8e6f5355f08b..36863fff2a99 100644
> --- a/arch/powerpc/kvm/book3s_hv_nestedv2.c
> +++ b/arch/powerpc/kvm/book3s_hv_nestedv2.c
> @@ -311,6 +311,10 @@ static int gs_msg_ops_vcpu_fill_info(struct kvmppc_gs_buff *gsb,
> rc = kvmppc_gse_put_u64(gsb, iden,
> vcpu->arch.vcore->vtb);
> break;
> + case KVMPPC_GSID_DPDES:
> + rc = kvmppc_gse_put_u64(gsb, iden,
> + vcpu->arch.vcore->dpdes);
> + break;
> case KVMPPC_GSID_LPCR:
> rc = kvmppc_gse_put_u64(gsb, iden,
> vcpu->arch.vcore->lpcr);
> @@ -543,6 +547,9 @@ static int gs_msg_ops_vcpu_refresh_info(struct kvmppc_gs_msg *gsm,
> case KVMPPC_GSID_VTB:
> vcpu->arch.vcore->vtb = kvmppc_gse_get_u64(gse);
> break;
> + case KVMPPC_GSID_DPDES:
> + vcpu->arch.vcore->dpdes = kvmppc_gse_get_u64(gse);
> + break;
> case KVMPPC_GSID_LPCR:
> vcpu->arch.vcore->lpcr = kvmppc_gse_get_u64(gse);
> break;
I would split all the wiring up of the DPDES GSID stuff into its own
patch, it obviously looks fine.
> diff --git a/arch/powerpc/kvm/test-guest-state-buffer.c b/arch/powerpc/kvm/test-guest-state-buffer.c
> index 4720b8dc8837..91ae660cfe21 100644
> --- a/arch/powerpc/kvm/test-guest-state-buffer.c
> +++ b/arch/powerpc/kvm/test-guest-state-buffer.c
> @@ -151,7 +151,7 @@ static void test_gs_bitmap(struct kunit *test)
> i++;
> }
>
> - for (u16 iden = KVMPPC_GSID_GPR(0); iden <= KVMPPC_GSID_CTRL; iden++) {
> + for (u16 iden = KVMPPC_GSID_GPR(0); iden <= KVMPPC_GSID_DPDES; iden++) {
> kvmppc_gsbm_set(&gsbm, iden);
> kvmppc_gsbm_set(&gsbm1, iden);
> KUNIT_EXPECT_TRUE(test, kvmppc_gsbm_test(&gsbm, iden));
It would be good to have a _LAST define for such loops. It's very easy
to miss when adding KVMPPC_GSID_DPDES that you need to grep for
KVMPPC_GSID_CTRL. Very easy to see that you need to update _LAST.
You just need to work out a good name for it since there's a few
"namespaces" of numbers with similar prefix. Good luck :)
Thanks,
Nick
On Mon, Jun 03, 2024 at 03:42:22PM GMT, Nicholas Piggin wrote:
> On Wed May 22, 2024 at 6:49 PM AEST, Gautam Menghani wrote:
> > Doorbell emulation is broken for KVM on PowerVM guests as support for
> > DPDES was not added in the initial patch series. Due to this, a KVM on
> > PowerVM guest cannot be booted with the XICS interrupt controller as
> > doorbells are to be setup in the initial probe path when using XICS
> > (pSeries_smp_probe()). Add DPDES support in the host KVM code to fix
> > doorbell emulation.
>
> This is broken when the KVM guest has SMT > 1? Or is it broken for SMT=1
> as well? Can you explain a bit more of what breaks if it's the latter?
Yes, doorbells are only setup when we use SMT>1 and interrupt controller
is XICS. So without this patch, L2 KOP guest with XICS IC mode and SMT>1
does not boot. SMT 1 is fine in all cases.
>
> > Fixes: 6ccbbc33f06a ("KVM: PPC: Add helper library for Guest State Buffers")
> > Cc: [email protected]
> > Signed-off-by: Gautam Menghani <[email protected]>
> > ---
> > v1 -> v1 resend:
> > 1. Add the stable tag
> >
> > Documentation/arch/powerpc/kvm-nested.rst | 4 +++-
> > arch/powerpc/include/asm/guest-state-buffer.h | 3 ++-
> > arch/powerpc/include/asm/kvm_book3s.h | 1 +
> > arch/powerpc/kvm/book3s_hv.c | 14 +++++++++++++-
> > arch/powerpc/kvm/book3s_hv_nestedv2.c | 7 +++++++
> > arch/powerpc/kvm/test-guest-state-buffer.c | 2 +-
> > 6 files changed, 27 insertions(+), 4 deletions(-)
> >
> > diff --git a/Documentation/arch/powerpc/kvm-nested.rst b/Documentation/arch/powerpc/kvm-nested.rst
> > index 630602a8aa00..5defd13cc6c1 100644
> > --- a/Documentation/arch/powerpc/kvm-nested.rst
> > +++ b/Documentation/arch/powerpc/kvm-nested.rst
> > @@ -546,7 +546,9 @@ table information.
> > +--------+-------+----+--------+----------------------------------+
> > | 0x1052 | 0x08 | RW | T | CTRL |
> > +--------+-------+----+--------+----------------------------------+
> > -| 0x1053-| | | | Reserved |
> > +| 0x1053 | 0x08 | RW | T | DPDES |
> > ++--------+-------+----+--------+----------------------------------+
> > +| 0x1054-| | | | Reserved |
> > | 0x1FFF | | | | |
> > +--------+-------+----+--------+----------------------------------+
> > | 0x2000 | 0x04 | RW | T | CR |
> > diff --git a/arch/powerpc/include/asm/guest-state-buffer.h b/arch/powerpc/include/asm/guest-state-buffer.h
> > index 808149f31576..d107abe1468f 100644
> > --- a/arch/powerpc/include/asm/guest-state-buffer.h
> > +++ b/arch/powerpc/include/asm/guest-state-buffer.h
> > @@ -81,6 +81,7 @@
> > #define KVMPPC_GSID_HASHKEYR 0x1050
> > #define KVMPPC_GSID_HASHPKEYR 0x1051
> > #define KVMPPC_GSID_CTRL 0x1052
> > +#define KVMPPC_GSID_DPDES 0x1053
> >
> > #define KVMPPC_GSID_CR 0x2000
> > #define KVMPPC_GSID_PIDR 0x2001
> > @@ -110,7 +111,7 @@
> > #define KVMPPC_GSE_META_COUNT (KVMPPC_GSE_META_END - KVMPPC_GSE_META_START + 1)
> >
> > #define KVMPPC_GSE_DW_REGS_START KVMPPC_GSID_GPR(0)
> > -#define KVMPPC_GSE_DW_REGS_END KVMPPC_GSID_CTRL
> > +#define KVMPPC_GSE_DW_REGS_END KVMPPC_GSID_DPDES
> > #define KVMPPC_GSE_DW_REGS_COUNT \
> > (KVMPPC_GSE_DW_REGS_END - KVMPPC_GSE_DW_REGS_START + 1)
> >
> > diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
> > index 3e1e2a698c9e..10618622d7ef 100644
> > --- a/arch/powerpc/include/asm/kvm_book3s.h
> > +++ b/arch/powerpc/include/asm/kvm_book3s.h
> > @@ -594,6 +594,7 @@ static inline u##size kvmppc_get_##reg(struct kvm_vcpu *vcpu) \
> >
> >
> > KVMPPC_BOOK3S_VCORE_ACCESSOR(vtb, 64, KVMPPC_GSID_VTB)
> > +KVMPPC_BOOK3S_VCORE_ACCESSOR(dpdes, 64, KVMPPC_GSID_DPDES)
> > KVMPPC_BOOK3S_VCORE_ACCESSOR_GET(arch_compat, 32, KVMPPC_GSID_LOGICAL_PVR)
> > KVMPPC_BOOK3S_VCORE_ACCESSOR_GET(lpcr, 64, KVMPPC_GSID_LPCR)
> > KVMPPC_BOOK3S_VCORE_ACCESSOR_SET(tb_offset, 64, KVMPPC_GSID_TB_OFFSET)
> > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> > index 35cb014a0c51..cf285e5153ba 100644
> > --- a/arch/powerpc/kvm/book3s_hv.c
> > +++ b/arch/powerpc/kvm/book3s_hv.c
> > @@ -4116,6 +4116,11 @@ static int kvmhv_vcpu_entry_nestedv2(struct kvm_vcpu *vcpu, u64 time_limit,
> > int trap;
> > long rc;
> >
> > + if (vcpu->arch.doorbell_request) {
> > + vcpu->arch.doorbell_request = 0;
> > + kvmppc_set_dpdes(vcpu, 1);
> > + }
>
> This probably looks okay... hmm, is the v1 KVM emulating doorbells
> correctly for SMT L2 guests? I wonder if doorbell emulation isn't
> broken there too because the L1 code looks to be passing in vc->dpdes
> but all the POWER9 emulation code uses doorbell_request.
>
Yes launching SMT L2 on V1 API fails with a kernel Oops, I'll see if I
can fix that as well.
> > +
> > io = &vcpu->arch.nestedv2_io;
> >
> > msr = mfmsr();
> > @@ -4278,9 +4283,16 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit,
> > if (kvmhv_on_pseries()) {
> > if (kvmhv_is_nestedv1())
> > trap = kvmhv_vcpu_entry_p9_nested(vcpu, time_limit, lpcr, tb);
> > - else
> > + else {
> > trap = kvmhv_vcpu_entry_nestedv2(vcpu, time_limit, lpcr, tb);
> >
> > + /* Remember doorbell if it is pending */
> > + if (kvmppc_get_dpdes(vcpu)) {
> > + vcpu->arch.doorbell_request = 1;
> > + kvmppc_set_dpdes(vcpu, 0);
> > + }
>
> This is adding an extra get state for every entry, not good. I don't
> think it's actually needed though. I don't think the L1 cares at this
> stage what the L2 DPDES state is. So you sholud be able to drop this
> hunk.
>
Yes ok.
> > + }
> > +
> > /* H_CEDE has to be handled now, not later */
> > if (trap == BOOK3S_INTERRUPT_SYSCALL && !nested &&
> > kvmppc_get_gpr(vcpu, 3) == H_CEDE) {
> > diff --git a/arch/powerpc/kvm/book3s_hv_nestedv2.c b/arch/powerpc/kvm/book3s_hv_nestedv2.c
> > index 8e6f5355f08b..36863fff2a99 100644
> > --- a/arch/powerpc/kvm/book3s_hv_nestedv2.c
> > +++ b/arch/powerpc/kvm/book3s_hv_nestedv2.c
> > @@ -311,6 +311,10 @@ static int gs_msg_ops_vcpu_fill_info(struct kvmppc_gs_buff *gsb,
> > rc = kvmppc_gse_put_u64(gsb, iden,
> > vcpu->arch.vcore->vtb);
> > break;
> > + case KVMPPC_GSID_DPDES:
> > + rc = kvmppc_gse_put_u64(gsb, iden,
> > + vcpu->arch.vcore->dpdes);
> > + break;
> > case KVMPPC_GSID_LPCR:
> > rc = kvmppc_gse_put_u64(gsb, iden,
> > vcpu->arch.vcore->lpcr);
> > @@ -543,6 +547,9 @@ static int gs_msg_ops_vcpu_refresh_info(struct kvmppc_gs_msg *gsm,
> > case KVMPPC_GSID_VTB:
> > vcpu->arch.vcore->vtb = kvmppc_gse_get_u64(gse);
> > break;
> > + case KVMPPC_GSID_DPDES:
> > + vcpu->arch.vcore->dpdes = kvmppc_gse_get_u64(gse);
> > + break;
> > case KVMPPC_GSID_LPCR:
> > vcpu->arch.vcore->lpcr = kvmppc_gse_get_u64(gse);
> > break;
>
> I would split all the wiring up of the DPDES GSID stuff into its own
> patch, it obviously looks fine.
>
Noted, will do.
> > diff --git a/arch/powerpc/kvm/test-guest-state-buffer.c b/arch/powerpc/kvm/test-guest-state-buffer.c
> > index 4720b8dc8837..91ae660cfe21 100644
> > --- a/arch/powerpc/kvm/test-guest-state-buffer.c
> > +++ b/arch/powerpc/kvm/test-guest-state-buffer.c
> > @@ -151,7 +151,7 @@ static void test_gs_bitmap(struct kunit *test)
> > i++;
> > }
> >
> > - for (u16 iden = KVMPPC_GSID_GPR(0); iden <= KVMPPC_GSID_CTRL; iden++) {
> > + for (u16 iden = KVMPPC_GSID_GPR(0); iden <= KVMPPC_GSID_DPDES; iden++) {
> > kvmppc_gsbm_set(&gsbm, iden);
> > kvmppc_gsbm_set(&gsbm1, iden);
> > KUNIT_EXPECT_TRUE(test, kvmppc_gsbm_test(&gsbm, iden));
>
> It would be good to have a _LAST define for such loops. It's very easy
> to miss when adding KVMPPC_GSID_DPDES that you need to grep for
> KVMPPC_GSID_CTRL. Very easy to see that you need to update _LAST.
>
> You just need to work out a good name for it since there's a few
> "namespaces" of numbers with similar prefix. Good luck :)
>
Well we already have a "KVMPPC_GSE_DW_REGS_END" defined, just missed to
use that.
> Thanks,
> Nick
On Mon Jun 3, 2024 at 5:09 PM AEST, Gautam Menghani wrote:
> On Mon, Jun 03, 2024 at 03:42:22PM GMT, Nicholas Piggin wrote:
> > On Wed May 22, 2024 at 6:49 PM AEST, Gautam Menghani wrote:
> > > Doorbell emulation is broken for KVM on PowerVM guests as support for
> > > DPDES was not added in the initial patch series. Due to this, a KVM on
> > > PowerVM guest cannot be booted with the XICS interrupt controller as
> > > doorbells are to be setup in the initial probe path when using XICS
> > > (pSeries_smp_probe()). Add DPDES support in the host KVM code to fix
> > > doorbell emulation.
> >
> > This is broken when the KVM guest has SMT > 1? Or is it broken for SMT=1
> > as well? Can you explain a bit more of what breaks if it's the latter?
>
> Yes, doorbells are only setup when we use SMT>1 and interrupt controller
> is XICS. So without this patch, L2 KOP guest with XICS IC mode and SMT>1
> does not boot. SMT 1 is fine in all cases.
Okay good. Make that clear in the changelog, ideally if you can give
a recipe the reader is able to recreate is good too, (e.g., run the
guest machine with -smp 4,threads=4 and xive=off boot parameter).
> > > Fixes: 6ccbbc33f06a ("KVM: PPC: Add helper library for Guest State Buffers")
> > > Cc: [email protected]
> > > Signed-off-by: Gautam Menghani <[email protected]>
> > > ---
> > > v1 -> v1 resend:
> > > 1. Add the stable tag
> > >
> > > Documentation/arch/powerpc/kvm-nested.rst | 4 +++-
> > > arch/powerpc/include/asm/guest-state-buffer.h | 3 ++-
> > > arch/powerpc/include/asm/kvm_book3s.h | 1 +
> > > arch/powerpc/kvm/book3s_hv.c | 14 +++++++++++++-
> > > arch/powerpc/kvm/book3s_hv_nestedv2.c | 7 +++++++
> > > arch/powerpc/kvm/test-guest-state-buffer.c | 2 +-
> > > 6 files changed, 27 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/Documentation/arch/powerpc/kvm-nested.rst b/Documentation/arch/powerpc/kvm-nested.rst
> > > index 630602a8aa00..5defd13cc6c1 100644
> > > --- a/Documentation/arch/powerpc/kvm-nested.rst
> > > +++ b/Documentation/arch/powerpc/kvm-nested.rst
> > > @@ -546,7 +546,9 @@ table information.
> > > +--------+-------+----+--------+----------------------------------+
> > > | 0x1052 | 0x08 | RW | T | CTRL |
> > > +--------+-------+----+--------+----------------------------------+
> > > -| 0x1053-| | | | Reserved |
> > > +| 0x1053 | 0x08 | RW | T | DPDES |
> > > ++--------+-------+----+--------+----------------------------------+
> > > +| 0x1054-| | | | Reserved |
> > > | 0x1FFF | | | | |
> > > +--------+-------+----+--------+----------------------------------+
> > > | 0x2000 | 0x04 | RW | T | CR |
> > > diff --git a/arch/powerpc/include/asm/guest-state-buffer.h b/arch/powerpc/include/asm/guest-state-buffer.h
> > > index 808149f31576..d107abe1468f 100644
> > > --- a/arch/powerpc/include/asm/guest-state-buffer.h
> > > +++ b/arch/powerpc/include/asm/guest-state-buffer.h
> > > @@ -81,6 +81,7 @@
> > > #define KVMPPC_GSID_HASHKEYR 0x1050
> > > #define KVMPPC_GSID_HASHPKEYR 0x1051
> > > #define KVMPPC_GSID_CTRL 0x1052
> > > +#define KVMPPC_GSID_DPDES 0x1053
> > >
> > > #define KVMPPC_GSID_CR 0x2000
> > > #define KVMPPC_GSID_PIDR 0x2001
> > > @@ -110,7 +111,7 @@
> > > #define KVMPPC_GSE_META_COUNT (KVMPPC_GSE_META_END - KVMPPC_GSE_META_START + 1)
> > >
> > > #define KVMPPC_GSE_DW_REGS_START KVMPPC_GSID_GPR(0)
> > > -#define KVMPPC_GSE_DW_REGS_END KVMPPC_GSID_CTRL
> > > +#define KVMPPC_GSE_DW_REGS_END KVMPPC_GSID_DPDES
> > > #define KVMPPC_GSE_DW_REGS_COUNT \
> > > (KVMPPC_GSE_DW_REGS_END - KVMPPC_GSE_DW_REGS_START + 1)
> > >
> > > diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
> > > index 3e1e2a698c9e..10618622d7ef 100644
> > > --- a/arch/powerpc/include/asm/kvm_book3s.h
> > > +++ b/arch/powerpc/include/asm/kvm_book3s.h
> > > @@ -594,6 +594,7 @@ static inline u##size kvmppc_get_##reg(struct kvm_vcpu *vcpu) \
> > >
> > >
> > > KVMPPC_BOOK3S_VCORE_ACCESSOR(vtb, 64, KVMPPC_GSID_VTB)
> > > +KVMPPC_BOOK3S_VCORE_ACCESSOR(dpdes, 64, KVMPPC_GSID_DPDES)
> > > KVMPPC_BOOK3S_VCORE_ACCESSOR_GET(arch_compat, 32, KVMPPC_GSID_LOGICAL_PVR)
> > > KVMPPC_BOOK3S_VCORE_ACCESSOR_GET(lpcr, 64, KVMPPC_GSID_LPCR)
> > > KVMPPC_BOOK3S_VCORE_ACCESSOR_SET(tb_offset, 64, KVMPPC_GSID_TB_OFFSET)
> > > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> > > index 35cb014a0c51..cf285e5153ba 100644
> > > --- a/arch/powerpc/kvm/book3s_hv.c
> > > +++ b/arch/powerpc/kvm/book3s_hv.c
> > > @@ -4116,6 +4116,11 @@ static int kvmhv_vcpu_entry_nestedv2(struct kvm_vcpu *vcpu, u64 time_limit,
> > > int trap;
> > > long rc;
> > >
> > > + if (vcpu->arch.doorbell_request) {
> > > + vcpu->arch.doorbell_request = 0;
> > > + kvmppc_set_dpdes(vcpu, 1);
> > > + }
> >
> > This probably looks okay... hmm, is the v1 KVM emulating doorbells
> > correctly for SMT L2 guests? I wonder if doorbell emulation isn't
> > broken there too because the L1 code looks to be passing in vc->dpdes
> > but all the POWER9 emulation code uses doorbell_request.
> >
>
> Yes launching SMT L2 on V1 API fails with a kernel Oops, I'll see if I
> can fix that as well.
Okay then I didn't miss something. Thanks v1 fix would be good too.
I think it should look something like putting doorbell_request into
hv_guest_state->dpdes that make the H_ENTER_NESTED call with.
For v1 you will need to restore the state back from dpdes back to
doorbell_request on exit, because the L0 doesn't keep it for you.
Thanks,
Nick