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Re: [PATCH for-5.0 v5 01/23] ppc/xive: Record the IPB in the associated
From: |
Cédric Le Goater |
Subject: |
Re: [PATCH for-5.0 v5 01/23] ppc/xive: Record the IPB in the associated NVT |
Date: |
Mon, 18 Nov 2019 16:57:26 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 |
On 18/11/2019 16:44, Greg Kurz wrote:
> On Fri, 15 Nov 2019 17:24:14 +0100
> Cédric Le Goater <address@hidden> wrote:
>
>> When an interrupt can not be presented to a vCPU, because it is not
>> running on any of the HW treads, the XIVE presenter updates the
>> Interrupt Pending Buffer register of the associated XIVE NVT
>> structure. This is only done if backlog is activated in the END but
>> this is generally the case.
>>
>> The current code assumes that the fields of the NVT structure is
>> architected with the same layout of the thread interrupt context
>> registers. Fix this assumption and define an offset for the IPB
>> register backup value in the NVT.
>>
>
> Does this fix a visible bug in the powernv machine ? If so,
> maybe worth describing the symptoms.
no. this is a preliminary work for escalation suppport and to dump
the contents of the NVT table.
> Anyway, this seems conforment to the XIVE spec I have, so FWIW:
FYI, the NVT structure evolves in the XIVE2 specs.
C.
> Reviewed-by: Greg Kurz <address@hidden>
>
>> Signed-off-by: Cédric Le Goater <address@hidden>
>> ---
>> include/hw/ppc/xive_regs.h | 1 +
>> hw/intc/xive.c | 11 +++++++++--
>> 2 files changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/hw/ppc/xive_regs.h b/include/hw/ppc/xive_regs.h
>> index 55307cd1533c..530f232b04f8 100644
>> --- a/include/hw/ppc/xive_regs.h
>> +++ b/include/hw/ppc/xive_regs.h
>> @@ -255,6 +255,7 @@ typedef struct XiveNVT {
>> uint32_t w2;
>> uint32_t w3;
>> uint32_t w4;
>> +#define NVT_W4_IPB PPC_BITMASK32(16, 23)
>> uint32_t w5;
>> uint32_t w6;
>> uint32_t w7;
>> diff --git a/hw/intc/xive.c b/hw/intc/xive.c
>> index 3d472e29c858..177663d2b43e 100644
>> --- a/hw/intc/xive.c
>> +++ b/hw/intc/xive.c
>> @@ -1607,14 +1607,21 @@ static void xive_router_end_notify(XiveRouter *xrtr,
>> uint8_t end_blk,
>> * - logical server : forward request to IVPE (not supported)
>> */
>> if (xive_end_is_backlog(&end)) {
>> + uint8_t ipb;
>> +
>> if (format == 1) {
>> qemu_log_mask(LOG_GUEST_ERROR,
>> "XIVE: END %x/%x invalid config: F1 & backlog\n",
>> end_blk, end_idx);
>> return;
>> }
>> - /* Record the IPB in the associated NVT structure */
>> - ipb_update((uint8_t *) &nvt.w4, priority);
>> + /*
>> + * Record the IPB in the associated NVT structure for later
>> + * use. The presenter will resend the interrupt when the vCPU
>> + * is dispatched again on a HW thread.
>> + */
>> + ipb = xive_get_field32(NVT_W4_IPB, nvt.w4) |
>> priority_to_ipb(priority);
>> + nvt.w4 = xive_set_field32(NVT_W4_IPB, nvt.w4, ipb);
>> xive_router_write_nvt(xrtr, nvt_blk, nvt_idx, &nvt, 4);
>>
>> /*
>