[{"id":3673703,"web_url":"http://patchwork.ozlabs.org/comment/3673703/","msgid":"<262bd67a-194b-407e-8727-ddb491b4996f@gmail.com>","list_archive_url":null,"date":"2026-04-06T11:02:26","subject":"Re: [PATCH 3/5] hw/ufs: Add idle operation","submitter":{"id":86755,"url":"http://patchwork.ozlabs.org/api/people/86755/","name":"Jeuk Kim","email":"jeuk20.kim@gmail.com"},"content":"On 4/2/2026 6:43 PM, Jaemyung Lee wrote:\n> When no I/O occurs, the UFS Device performs various internal operations.\n> To emulate this, adds a timer that periodically checks the current I/O\n> status of the device and call the ufs_process_idle() function when idle.\n>\n> Signed-off-by: Jaemyung Lee \n> ---\n> hw/ufs/ufs.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++\n> hw/ufs/ufs.h | 2 ++\n> 2 files changed, 49 insertions(+)\n>\n> diff --git a/hw/ufs/ufs.c b/hw/ufs/ufs.c\n> index 69f82ab462d135fe6cda479891f9d8f26d19be9a..111ce3c3a0b03a1ead722f48b799e3ed0c403cce 100644\n> --- a/hw/ufs/ufs.c\n> +++ b/hw/ufs/ufs.c\n> @@ -1801,6 +1801,47 @@ static void ufs_sendback_req(void *opaque)\n> ufs_irq_check(u);\n> }\n> \n> +static void ufs_process_idle(UfsHc *u)\n> +{\n> + /* Currently do nothing */\n> + return;\n> +}\n> +\n> +static inline bool ufs_check_idle(UfsHc *u)\n> +{\n> + return !u->reg.utrldbr;\n> +}\n> +\n> +static inline bool ufs_mcq_check_idle(UfsHc *u)\n> +{\n> + for (int i = 0; i < ARRAY_SIZE(u->sq); i++) {\n> + if (!ufs_mcq_sq_empty(u, i)) {\n> + return false;\n> + }\n> + }\n> +\n> + for (int i = 0; i < ARRAY_SIZE(u->cq); i++) {\n> + if (!ufs_mcq_cq_empty(u, i)) {\n> + return false;\n> + }\n> + }\n> +\n> + return true;\n> +}\n\nI think the idle check needs to consider the internal MCQ request state \nas well, not just the guest-visible SQ/CQ state.\n\nIn MCQ, a request goes through\nSQ free list -> RUNNING -> COMPLETE -> CQ pending list -> guest CQ \nwrite-back -> free list again.\n\nSo a request can already be dequeued from SQ and still be \nUFS_REQUEST_RUNNING, or it can already be completed and still be pending \nCQ write-back.\n\nThe idle check should also cover active internal requests and pending CQ \ncompletions, not just SQ/CQ head/tail visibility.\n\n\n\n> +\n> +#define UFS_IDLE_TIMER_TICK 100 /* 0.1s */\n> +static void ufs_idle_timer_cb(void *opaque)\n> +{\n> + UfsHc *u = opaque;\n> + int64_t now = qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL_RT);\n> +\n> + if (ufs_check_idle(u) && ufs_mcq_check_idle(u)) {\n> + ufs_process_idle(u);\n> + }\n> +\n> + timer_mod(&u->idle_timer, now + UFS_IDLE_TIMER_TICK);\n> +}\n> +\n> static bool ufs_check_constraints(UfsHc *u, Error **errp)\n> {\n> if (u->params.nutrs > UFS_MAX_NUTRS) {\n> @@ -1863,6 +1904,7 @@ static void ufs_init_hc(UfsHc *u)\n> uint32_t cap = 0;\n> uint32_t mcqconfig = 0;\n> uint32_t mcqcap = 0;\n> + int64_t now = qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL_RT);\n> \n> u->reg_size = pow2ceil(ufs_reg_size(u));\n> \n> @@ -1959,6 +2001,9 @@ static void ufs_init_hc(UfsHc *u)\n> * dynamically\n> */\n> u->temperature = UFS_TEMPERATURE;\n> +\n> + timer_init_ms(&u->idle_timer, QEMU_CLOCK_VIRTUAL_RT, ufs_idle_timer_cb, u);\n> + timer_mod(&u->idle_timer, now + UFS_IDLE_TIMER_TICK);\n> }\n> \n> static void ufs_realize(PCIDevice *pci_dev, Error **errp)\n> @@ -1986,6 +2031,8 @@ static void ufs_exit(PCIDevice *pci_dev)\n> {\n> UfsHc *u = UFS(pci_dev);\n> \n> + timer_del(&u->idle_timer);\n> +\n> qemu_free_irq(u->irq);\n> \n> qemu_bh_delete(u->doorbell_bh);\n> diff --git a/hw/ufs/ufs.h b/hw/ufs/ufs.h\n> index 13d964c5ae5ec430a98b2ef71987cb9279e9a317..b5f040302129f4d02732ddd20ef82eb33c41922a 100644\n> --- a/hw/ufs/ufs.h\n> +++ b/hw/ufs/ufs.h\n> @@ -148,6 +148,8 @@ typedef struct UfsHc {\n> UfsCq *cq[UFS_MAX_MCQ_QNUM];\n> \n> uint8_t temperature;\n> +\n> + QEMUTimer idle_timer;\n> } UfsHc;\n> \n> static inline uint32_t ufs_mcq_sq_tail(UfsHc *u, uint32_t qid)\n>","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=ZjwAiuqM;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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