[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <cb1b1042-6bc5-d294-4fa7-26534b921e42@amd.com>
Date: Wed, 28 Dec 2022 14:10:30 +0530
From: Vasant Hegde <vasant.hegde@....com>
To: Peter Zijlstra <peterz@...radead.org>,
torvalds@...ux-foundation.org
Cc: corbet@....net, will@...nel.org, boqun.feng@...il.com,
mark.rutland@....com, catalin.marinas@....com, dennis@...nel.org,
tj@...nel.org, cl@...ux.com, hca@...ux.ibm.com, gor@...ux.ibm.com,
agordeev@...ux.ibm.com, borntraeger@...ux.ibm.com,
svens@...ux.ibm.com, Herbert Xu <herbert@...dor.apana.org.au>,
davem@...emloft.net, tglx@...utronix.de, mingo@...hat.com,
bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
hpa@...or.com, joro@...tes.org, suravee.suthikulpanit@....com,
robin.murphy@....com, dwmw2@...radead.org,
baolu.lu@...ux.intel.com, Arnd Bergmann <arnd@...db.de>,
penberg@...nel.org, rientjes@...gle.com, iamjoonsoo.kim@....com,
Andrew Morton <akpm@...ux-foundation.org>, vbabka@...e.cz,
roman.gushchin@...ux.dev, 42.hyeyoo@...il.com,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linux-s390@...r.kernel.org,
linux-crypto@...r.kernel.org, iommu@...ts.linux.dev,
linux-arch@...r.kernel.org
Subject: Re: [RFC][PATCH 09/12] x86,amd_iommu: Replace cmpxchg_double()
On 12/19/2022 9:05 PM, Peter Zijlstra wrote:
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---
> drivers/iommu/amd/amd_iommu_types.h | 9 +++++++--
> drivers/iommu/amd/iommu.c | 10 ++++------
> 2 files changed, 11 insertions(+), 8 deletions(-)
>
> --- a/drivers/iommu/amd/amd_iommu_types.h
> +++ b/drivers/iommu/amd/amd_iommu_types.h
> @@ -979,8 +979,13 @@ union irte_ga_hi {
> };
>
> struct irte_ga {
> - union irte_ga_lo lo;
> - union irte_ga_hi hi;
> + union {
> + struct {
> + union irte_ga_lo lo;
> + union irte_ga_hi hi;
> + };
> + u128 irte;
> + };
> };
>
> struct irq_2_irte {
> --- a/drivers/iommu/amd/iommu.c
> +++ b/drivers/iommu/amd/iommu.c
> @@ -2992,10 +2992,10 @@ static int alloc_irq_index(struct amd_io
> static int modify_irte_ga(struct amd_iommu *iommu, u16 devid, int index,
> struct irte_ga *irte, struct amd_ir_data *data)
> {
> - bool ret;
> struct irq_remap_table *table;
> - unsigned long flags;
> struct irte_ga *entry;
> + unsigned long flags;
> + u128 old;
>
> table = get_irq_table(iommu, devid);
> if (!table)
> @@ -3006,16 +3006,14 @@ static int modify_irte_ga(struct amd_iom
> entry = (struct irte_ga *)table->table;
> entry = &entry[index];
>
> - ret = cmpxchg_double(&entry->lo.val, &entry->hi.val,
> - entry->lo.val, entry->hi.val,
> - irte->lo.val, irte->hi.val);
> /*
> * We use cmpxchg16 to atomically update the 128-bit IRTE,
> * and it cannot be updated by the hardware or other processors
> * behind us, so the return value of cmpxchg16 should be the
> * same as the old value.
> */
> - WARN_ON(!ret);
> + old = entry->irte;
> + WARN_ON(!try_cmpxchg128(&entry->irte, &old, irte->irte));
Changes looks good to me. I have tested it on AMD system and it works fine.
-Vasant
Powered by blists - more mailing lists