Re: [PATCH 09/17] ppc/pnv: move nest_regs_mr to PnvPHB4

From: "Cédric Le Goater" <clg@kaod.org>
To: Daniel Henrique Barboza <danielhb413@gmail.com>, <qemu-devel@nongnu.org>
Cc: qemu-ppc@nongnu.org, david@gibson.dropbear.id.au
Subject: Re: [PATCH 09/17] ppc/pnv: move nest_regs_mr to PnvPHB4
Date: Fri, 14 Jan 2022 11:42:27 +0100	[thread overview]
Message-ID: <8ecb83eb-ce0c-b8d4-fd8a-d48d1dadc430@kaod.org> (raw)
In-Reply-To: <20220113192952.911188-10-danielhb413@gmail.com>

On 1/13/22 20:29, Daniel Henrique Barboza wrote:
> We're now able to cleanly move nest_regs_mr to the PnvPHB4 device.
> 
> One thing of notice here is the need to use a phb->stack->pec pointer
> because pnv_pec_stk_nest_xscom_write requires a PEC object. Another
> thing that can be noticed in the use of 'stack->stack_no' that still
> remains throughout the XSCOM code.
> 
> After moving all MemoryRegions to the PnvPHB4 object, this illustrates
> what is the remaining role of the stack: provide a PEC pointer and the
> 'stack_no' information. If we can provide these in the PnvPHB4 object
> instead (spoiler: we can, and we will), the PnvPhb4PecStack device will
> be deprecated and can be removed.
> 
> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>


Reviewed-by: Cédric Le Goater <clg@kaod.org>

Thanks,

C.

> ---
>   hw/pci-host/pnv_phb4.c         | 16 +++++++---------
>   include/hw/pci-host/pnv_phb4.h |  3 +--
>   2 files changed, 8 insertions(+), 11 deletions(-)
> 
> diff --git a/hw/pci-host/pnv_phb4.c b/hw/pci-host/pnv_phb4.c
> index 0f4464ec67..37bab10fcb 100644
> --- a/hw/pci-host/pnv_phb4.c
> +++ b/hw/pci-host/pnv_phb4.c
> @@ -861,8 +861,7 @@ const MemoryRegionOps pnv_phb4_xscom_ops = {
>   static uint64_t pnv_pec_stk_nest_xscom_read(void *opaque, hwaddr addr,
>                                               unsigned size)
>   {
> -    PnvPhb4PecStack *stack = PNV_PHB4_PEC_STACK(opaque);
> -    PnvPHB4 *phb = stack->phb;
> +    PnvPHB4 *phb = PNV_PHB4(opaque);
>       uint32_t reg = addr >> 3;
>   
>       /* TODO: add list of allowed registers and error out if not */
> @@ -982,9 +981,8 @@ static void pnv_pec_stk_update_map(PnvPHB4 *phb)
>   static void pnv_pec_stk_nest_xscom_write(void *opaque, hwaddr addr,
>                                            uint64_t val, unsigned size)
>   {
> -    PnvPhb4PecStack *stack = PNV_PHB4_PEC_STACK(opaque);
> -    PnvPHB4 *phb = stack->phb;
> -    PnvPhb4PecState *pec = stack->pec;
> +    PnvPHB4 *phb = PNV_PHB4(opaque);
> +    PnvPhb4PecState *pec = phb->stack->pec;
>       uint32_t reg = addr >> 3;
>   
>       switch (reg) {
> @@ -1470,10 +1468,10 @@ static void pnv_phb4_xscom_realize(PnvPHB4 *phb)
>       assert(pec);
>   
>       /* Initialize the XSCOM regions for the stack registers */
> -    snprintf(name, sizeof(name), "xscom-pec-%d.%d-nest-stack-%d",
> +    snprintf(name, sizeof(name), "xscom-pec-%d.%d-nest-phb-%d",
>                pec->chip_id, pec->index, stack->stack_no);
> -    pnv_xscom_region_init(&stack->nest_regs_mr, OBJECT(stack),
> -                          &pnv_pec_stk_nest_xscom_ops, stack, name,
> +    pnv_xscom_region_init(&phb->nest_regs_mr, OBJECT(phb),
> +                          &pnv_pec_stk_nest_xscom_ops, phb, name,
>                             PHB4_PEC_NEST_STK_REGS_COUNT);
>   
>       snprintf(name, sizeof(name), "xscom-pec-%d.%d-pci-phb-%d",
> @@ -1494,7 +1492,7 @@ static void pnv_phb4_xscom_realize(PnvPHB4 *phb)
>       /* Populate the XSCOM address space. */
>       pnv_xscom_add_subregion(pec->chip,
>                               pec_nest_base + 0x40 * (stack->stack_no + 1),
> -                            &stack->nest_regs_mr);
> +                            &phb->nest_regs_mr);
>       pnv_xscom_add_subregion(pec->chip,
>                               pec_pci_base + 0x40 * (stack->stack_no + 1),
>                               &phb->pci_regs_mr);
> diff --git a/include/hw/pci-host/pnv_phb4.h b/include/hw/pci-host/pnv_phb4.h
> index a7e08772c1..1d53dda0ed 100644
> --- a/include/hw/pci-host/pnv_phb4.h
> +++ b/include/hw/pci-host/pnv_phb4.h
> @@ -115,6 +115,7 @@ struct PnvPHB4 {
>       /* Nest registers */
>   #define PHB4_PEC_NEST_STK_REGS_COUNT  0x17
>       uint64_t nest_regs[PHB4_PEC_NEST_STK_REGS_COUNT];
> +    MemoryRegion nest_regs_mr;
>   
>       /* Memory windows from PowerBus to PHB */
>       MemoryRegion phbbar;
> @@ -169,8 +170,6 @@ struct PnvPhb4PecStack {
>       /* My own stack number */
>       uint32_t stack_no;
>   
> -    MemoryRegion nest_regs_mr;
> -
>       /* PHB pass-through XSCOM */
>       MemoryRegion phb_regs_mr;
>   
>