[PATCH] arch/powerpc/kvm: Fix doorbell emulation by adding DPDES support

[PATCH] arch/powerpc/kvm: Fix doorbell emulation by adding DPDES support

[Gautam Menghani]

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")
Signed-off-by: Gautam Menghani <gautam@linux.ibm.com>
---
 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

Re: [PATCH] arch/powerpc/kvm: Fix doorbell emulation by adding DPDES support

[kernel test robot]

Hi,

Thanks for your patch.

FYI: kernel test robot notices the stable kernel rule is not satisfied.

The check is based on https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#option-1

Rule: add the tag "Cc: stable@vger.kernel.org" in the sign-off area to have the patch automatically included in the stable tree.
Subject: [PATCH] arch/powerpc/kvm: Fix doorbell emulation by adding DPDES support
Link: https://lore.kernel.org/stable/20240522082838.121769-1-gautam%40linux.ibm.com

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH] arch/powerpc/kvm: Fix doorbell emulation by adding DPDES support

[Michael Ellerman]

kernel test robot <lkp@intel.com> writes:
> Hi,
>
> Thanks for your patch.

I found this report confusing.

It seems like it's saying a patch with "Fixes: ..." *must* include a
"Cc: stable" tag, but that is wrong, it's up to the developer to decide.

What it's trying to say is that the patch was Cc'ed via mail to
stable@vger.kernel.org and that is not the correct way to request stable
inclusion.

So can I suggest the report begins with something like:

  Your patch was Cc'ed via mail to stable@vger.kernel.org but that is
  not the correct way to requestion stable inclusion, the correct method
  is ....

> FYI: kernel test robot notices the stable kernel rule is not satisfied.
>
> The check is based on https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#option-1
>
> Rule: add the tag "Cc: stable@vger.kernel.org" in the sign-off area to have the patch automatically included in the stable tree.
> Subject: [PATCH] arch/powerpc/kvm: Fix doorbell emulation by adding DPDES support
> Link: https://lore.kernel.org/stable/20240522082838.121769-1-gautam%40linux.ibm.com


cheers

Re: [PATCH] arch/powerpc/kvm: Fix doorbell emulation by adding DPDES support

[Yujie Liu]

Hi Michael,

On Thu, May 23, 2024 at 12:05:03PM +1000, Michael Ellerman wrote:
> kernel test robot <lkp@intel.com> writes:
> > Hi,
> >
> > Thanks for your patch.
> 
> I found this report confusing.
> 
> It seems like it's saying a patch with "Fixes: ..." *must* include a
> "Cc: stable" tag, but that is wrong, it's up to the developer to decide.
> 
> What it's trying to say is that the patch was Cc'ed via mail to
> stable@vger.kernel.org and that is not the correct way to request stable
> inclusion.
> 
> So can I suggest the report begins with something like:
> 
>   Your patch was Cc'ed via mail to stable@vger.kernel.org but that is
>   not the correct way to requestion stable inclusion, the correct method
>   is ....
> 
> > FYI: kernel test robot notices the stable kernel rule is not satisfied.
> >
> > The check is based on https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#option-1
> >
> > Rule: add the tag "Cc: stable@vger.kernel.org" in the sign-off area to have the patch automatically included in the stable tree.

Sorry for causing any confusion. This report actually suggests to add a
"Cc: stable@vger.kernel.org" tag in the sign-off area as well, despite
having "Cc: stable@vger.kernel.org" in the email header.

  Cc: stable@vger.kernel.org
  Fixes: 6ccbbc33f06a ("KVM: PPC: Add helper library for Guest State Buffers")
  Signed-off-by: ...

Not sure if we interpret the documentation correctly or not. Please kindly
correct us if we have any misunderstanding, and we will fix the bot to
provide more accurate suggestions in the report.

https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#option-1

Thanks,
Yujie

> > Subject: [PATCH] arch/powerpc/kvm: Fix doorbell emulation by adding DPDES support
> > Link: https://lore.kernel.org/stable/20240522082838.121769-1-gautam%40linux.ibm.com
> 
> 
> cheers
> 

Re: [PATCH] arch/powerpc/kvm: Fix doorbell emulation by adding DPDES support

[Yujie Liu]

On Thu, May 23, 2024 at 12:05:03PM +1000, Michael Ellerman wrote:
> kernel test robot <lkp@intel.com> writes:
> > Hi,
> >
> > Thanks for your patch.
> 
> I found this report confusing.
> 
> It seems like it's saying a patch with "Fixes: ..." *must* include a
> "Cc: stable" tag, but that is wrong, it's up to the developer to decide.

We actually wish to notify that to have a patch automatically picked up
for stable inclusion, it should add a "CC: stable" tag, regardless of
whether it is a "Fixes:" patch or not.

Sorry for any confusion. We will consider improving the wording.

Thanks,
Yujie

> 
> What it's trying to say is that the patch was Cc'ed via mail to
> stable@vger.kernel.org and that is not the correct way to request stable
> inclusion.
> 
> So can I suggest the report begins with something like:
> 
>   Your patch was Cc'ed via mail to stable@vger.kernel.org but that is
>   not the correct way to requestion stable inclusion, the correct method
>   is ....
> 
> > FYI: kernel test robot notices the stable kernel rule is not satisfied.
> >
> > The check is based on https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#option-1
> >
> > Rule: add the tag "Cc: stable@vger.kernel.org" in the sign-off area to have the patch automatically included in the stable tree.
> > Subject: [PATCH] arch/powerpc/kvm: Fix doorbell emulation by adding DPDES support
> > Link: https://lore.kernel.org/stable/20240522082838.121769-1-gautam%40linux.ibm.com
> 
> 
> cheers
> 

Re: [PATCH] arch/powerpc/kvm: Fix doorbell emulation by adding DPDES support

[Gautam Menghani]

Hello,

Please review this patch and let me know if any changes are needed.

Thanks,
Gautam

Re: [PATCH] arch/powerpc/kvm: Fix doorbell emulation by adding DPDES support

[Greg KH]

On Fri, May 31, 2024 at 10:54:58AM +0530, Gautam Menghani wrote:
> Hello,
> 
> Please review this patch and let me know if any changes are needed.

There already was review comments on it, why ignore them?

Re: [PATCH] arch/powerpc/kvm: Fix doorbell emulation by adding DPDES support

[Gautam Menghani]

On Fri, May 31, 2024 at 08:09:13AM GMT, Greg KH wrote:
> On Fri, May 31, 2024 at 10:54:58AM +0530, Gautam Menghani wrote:
> > Hello,
> > 
> > Please review this patch and let me know if any changes are needed.
> 
> There already was review comments on it, why ignore them?

Sorry I pinged on the wrong thread, I had already addressed the stable
tag issue in a resend - https://lore.kernel.org/linuxppc-dev/20240522084949.123148-1-gautam@linux.ibm.com/

Thanks,
Gautam