The DPDES support for doorbell emulation and handling for KVM on PAPR guests was added in Linux via [1]. Subsequently, a new GSB element for DPDES was added in Linux; the same has been missing in QEMU L0. Add support for DPDES register's APIv2 GSB element and required handling in `spapr_nested.c`.
Currently, booting a KVM guest inside a QEMU TCG guest fails with the below crash. The crash is encountered when GUEST_RUN_VCPU hcall made into QEMU TCG L0 fails because H_INVALID_ELEMENT_VALUE is returned as the mapping of the element ID corresponding to DPDES (unknown to QEMU TCG L0) in GSR (Guest State Request) of TCG guest's KVM to the GSB (Guest State Buffer) elements of QEMU TCG L0 fails. KVM: unknown exit, hardware reason ffffffffffffffea NIP 0000000000000100 LR 0000000000000000 CTR 0000000000000000 XER 0000000000000000 CPU#0 MSR 0000000000003000 HID0 0000000000000000 HF 6c002000 iidx 3 didx 3 TB 00000000 00000000 DECR 0 GPR00 0000000000000000 0000000000000000 0000000000000000 000000007fe00000 GPR04 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR08 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR12 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR16 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR20 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR24 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR28 0000000000000000 0000000000000000 0000000000000000 0000000000000000 CR 00000000 [ - - - - - - - - ] RES 000@ffffffffffffffff SRR0 0000000000000000 SRR1 0000000000000000 PVR 0000000000801200 VRSAVE 0000000000000000 SPRG0 0000000000000000 SPRG1 0000000000000000 SPRG2 0000000000000000 SPRG3 0000000000000000 SPRG4 0000000000000000 SPRG5 0000000000000000 SPRG6 0000000000000000 SPRG7 0000000000000000 HSRR0 0000000000000000 HSRR1 0000000000000000 CFAR 0000000000000000 LPCR 0000000000560413 PTCR 0000000000000000 DAR 0000000000000000 DSISR 0000000000000000 Fix this by adding the required support and handling in QEMU TCG L0. [1] https://lore.kernel.org/all/20240605113913.83715-1-gau...@linux.ibm.com/ Fixes: 4a575f9a0567 ("spapr: nested: Initialize the GSB elements lookup table.") Suggested-by: Harsh Prateek Bora <hars...@linux.ibm.com> Reviewed-by: Vaibhav Jain <vaib...@linux.ibm.com> Signed-off-by: Amit Machhiwal <amach...@linux.ibm.com> --- hw/ppc/spapr_nested.c | 3 +++ include/hw/ppc/spapr_nested.h | 3 ++- 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/hw/ppc/spapr_nested.c b/hw/ppc/spapr_nested.c index c02785756c1e..b696ad537a77 100644 --- a/hw/ppc/spapr_nested.c +++ b/hw/ppc/spapr_nested.c @@ -194,6 +194,7 @@ static void nested_save_state(struct nested_ppc_state *save, PowerPCCPU *cpu) save->fscr = env->spr[SPR_FSCR]; save->pspb = env->spr[SPR_PSPB]; save->ctrl = env->spr[SPR_CTRL]; + save->dpdes = env->spr[SPR_DPDES]; save->vrsave = env->spr[SPR_VRSAVE]; save->dar = env->spr[SPR_DAR]; save->dsisr = env->spr[SPR_DSISR]; @@ -293,6 +294,7 @@ static void nested_load_state(PowerPCCPU *cpu, struct nested_ppc_state *load) env->spr[SPR_FSCR] = load->fscr; env->spr[SPR_PSPB] = load->pspb; env->spr[SPR_CTRL] = load->ctrl; + env->spr[SPR_DPDES] = load->dpdes; env->spr[SPR_VRSAVE] = load->vrsave; env->spr[SPR_DAR] = load->dar; env->spr[SPR_DSISR] = load->dsisr; @@ -982,6 +984,7 @@ struct guest_state_element_type guest_state_element_types[] = { GUEST_STATE_ELEMENT_ENV_DW(GSB_VCPU_SPR_FSCR, fscr), GUEST_STATE_ELEMENT_ENV_W(GSB_VCPU_SPR_PSPB, pspb), GUEST_STATE_ELEMENT_ENV_DW(GSB_VCPU_SPR_CTRL, ctrl), + GUEST_STATE_ELEMENT_ENV_DW(GSB_VCPU_SPR_DPDES, dpdes), GUEST_STATE_ELEMENT_ENV_W(GSB_VCPU_SPR_VRSAVE, vrsave), GUEST_STATE_ELEMENT_ENV_DW(GSB_VCPU_SPR_DAR, dar), GUEST_STATE_ELEMENT_ENV_W(GSB_VCPU_SPR_DSISR, dsisr), diff --git a/include/hw/ppc/spapr_nested.h b/include/hw/ppc/spapr_nested.h index 93ef14adcc5e..3b5cd993c256 100644 --- a/include/hw/ppc/spapr_nested.h +++ b/include/hw/ppc/spapr_nested.h @@ -99,7 +99,8 @@ #define GSB_VCPU_SPR_HASHKEYR 0x1050 #define GSB_VCPU_SPR_HASHPKEYR 0x1051 #define GSB_VCPU_SPR_CTRL 0x1052 - /* RESERVED 0x1053 - 0x1FFF */ +#define GSB_VCPU_SPR_DPDES 0x1053 + /* RESERVED 0x1054 - 0x1FFF */ #define GSB_VCPU_SPR_CR 0x2000 #define GSB_VCPU_SPR_PIDR 0x2001 #define GSB_VCPU_SPR_DSISR 0x2002 base-commit: aa54f5be44be786636a5d51cc1612ad208a24849 -- 2.47.0
