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: stable@vger.kernel.org Signed-off-by: Gautam Menghani gautam@linux.ibm.com
v1 -> v1 resend:
- 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