From: Jan Beulich <jbeulich@suse.com>
To: Paul Durrant <paul@xen.org>
Cc: xen-devel@lists.xenproject.org,
Paul Durrant <pdurrant@amazon.com>,
Kevin Tian <kevin.tian@intel.com>
Subject: Re: [PATCH v4 13/14] vtd: use a bit field for context_entry
Date: Thu, 6 Aug 2020 14:46:51 +0200 [thread overview]
Message-ID: <6de24196-019c-f91c-5cca-0971676a9b38@suse.com> (raw)
In-Reply-To: <20200804134209.8717-14-paul@xen.org>
On 04.08.2020 15:42, Paul Durrant wrote:
> @@ -208,35 +209,53 @@ struct root_entry {
> do { (r).ctp = ((val) >> PAGE_SHIFT_4K); } while (0)
>
> struct context_entry {
> - u64 lo;
> - u64 hi;
> + union {
> + __uint128_t val;
> + struct { uint64_t lo, hi; };
> + struct {
> + /* 0 - 63 */
> + uint64_t p:1;
> + uint64_t fpd:1;
> + uint64_t tt:2;
> + uint64_t reserved0:8;
> + uint64_t slptp:52;
> +
> + /* 64 - 127 */
> + uint64_t aw:3;
> + uint64_t ignored:4;
> + uint64_t reserved1:1;
> + uint64_t did:16;
> + uint64_t reserved2:40;
> + };
> + };
> };
> -#define ROOT_ENTRY_NR (PAGE_SIZE_4K/sizeof(struct root_entry))
> -#define context_present(c) ((c).lo & 1)
> -#define context_fault_disable(c) (((c).lo >> 1) & 1)
> -#define context_translation_type(c) (((c).lo >> 2) & 3)
> -#define context_address_root(c) ((c).lo & PAGE_MASK_4K)
> -#define context_address_width(c) ((c).hi & 7)
> -#define context_domain_id(c) (((c).hi >> 8) & ((1 << 16) - 1))
> -
> -#define context_set_present(c) do {(c).lo |= 1;} while(0)
> -#define context_clear_present(c) do {(c).lo &= ~1;} while(0)
> -#define context_set_fault_enable(c) \
> - do {(c).lo &= (((u64)-1) << 2) | 1;} while(0)
> -
> -#define context_set_translation_type(c, val) do { \
> - (c).lo &= (((u64)-1) << 4) | 3; \
> - (c).lo |= (val & 3) << 2; \
> - } while(0)
> +
> +#define context_present(c) (c).p
> +#define context_set_present(c) do { (c).p = 1; } while (0)
> +#define context_clear_present(c) do { (c).p = 0; } while (0)
> +
> +#define context_fault_disable(c) (c).fpd
> +#define context_set_fault_enable(c) do { (c).fpd = 1; } while (0)
> +
> +#define context_translation_type(c) (c).tt
> +#define context_set_translation_type(c, val) do { (c).tt = val; } while (0)
> #define CONTEXT_TT_MULTI_LEVEL 0
> #define CONTEXT_TT_DEV_IOTLB 1
> #define CONTEXT_TT_PASS_THRU 2
>
> -#define context_set_address_root(c, val) \
> - do {(c).lo &= 0xfff; (c).lo |= (val) & PAGE_MASK_4K ;} while(0)
> +#define context_slptp(c) ((c).slptp << PAGE_SHIFT_4K)
> +#define context_set_slptp(c, val) \
> + do { (c).slptp = (val) >> PAGE_SHIFT_4K; } while (0)
Presumably "slptp" is in line with the doc, but "address_root" is
quite a bit more readable. I wonder if I could talk you into
restoring the old (or some similar) names.
More generally, and more so here than perhaps already on the previous
patch - are these helper macros useful to have anymore?
> +#define context_address_width(c) (c).aw
> #define context_set_address_width(c, val) \
> - do {(c).hi &= 0xfffffff8; (c).hi |= (val) & 7;} while(0)
> -#define context_clear_entry(c) do {(c).lo = 0; (c).hi = 0;} while(0)
> + do { (c).aw = (val); } while (0)
> +
> +#define context_did(c) (c).did
> +#define context_set_did(c, val) \
> + do { (c).did = (val); } while (0)
> +
> +#define context_clear_entry(c) do { (c).val = 0; } while (0)
While this is in line with previous code, I'm concerned:
domain_context_unmap_one() has
context_clear_present(*context);
context_clear_entry(*context);
No barrier means no guarantee of ordering. I'd drop clear_present()
here and make clear_entry() properly ordered. This, I think, will at
the same time render the __uint128_t field unused and hence
unnecessary again.
Also comments given on the previous patch apply respectively here.
Jan
next prev parent reply other threads:[~2020-08-06 12:47 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-04 13:41 [PATCH v4 00/14] IOMMU cleanup Paul Durrant
2020-08-04 13:41 ` [PATCH v4 01/14] x86/iommu: re-arrange arch_iommu to separate common fields Paul Durrant
2020-08-14 6:14 ` Tian, Kevin
2020-08-04 13:41 ` [PATCH v4 02/14] x86/iommu: add common page-table allocator Paul Durrant
2020-08-05 15:39 ` Jan Beulich
2020-08-04 13:41 ` [PATCH v4 03/14] x86/iommu: convert VT-d code to use new page table allocator Paul Durrant
2020-08-14 6:41 ` Tian, Kevin
2020-08-14 7:16 ` Durrant, Paul
2020-08-04 13:41 ` [PATCH v4 04/14] x86/iommu: convert AMD IOMMU " Paul Durrant
2020-08-04 13:42 ` [PATCH v4 05/14] iommu: remove unused iommu_ops method and tasklet Paul Durrant
2020-08-04 13:42 ` [PATCH v4 06/14] iommu: flush I/O TLB if iommu_map() or iommu_unmap() fail Paul Durrant
2020-08-05 16:06 ` Jan Beulich
2020-08-05 16:18 ` Paul Durrant
2020-08-06 11:41 ` Jan Beulich
2020-08-14 6:53 ` Tian, Kevin
2020-08-14 7:19 ` Durrant, Paul
2020-08-04 13:42 ` [PATCH v4 07/14] iommu: make map, unmap and flush all take both an order and a count Paul Durrant
2020-08-06 9:57 ` Jan Beulich
2020-08-11 11:00 ` Durrant, Paul
2020-08-14 6:57 ` Tian, Kevin
2020-08-04 13:42 ` [PATCH v4 08/14] remove remaining uses of iommu_legacy_map/unmap Paul Durrant
2020-08-06 10:28 ` Jan Beulich
2020-08-12 9:36 ` [EXTERNAL] " Paul Durrant
2020-08-04 13:42 ` [PATCH v4 09/14] common/grant_table: batch flush I/O TLB Paul Durrant
2020-08-06 11:49 ` Jan Beulich
2020-08-04 13:42 ` [PATCH v4 10/14] iommu: remove the share_p2m operation Paul Durrant
2020-08-06 12:18 ` Jan Beulich
2020-08-14 7:04 ` Tian, Kevin
2020-08-04 13:42 ` [PATCH v4 11/14] iommu: stop calling IOMMU page tables 'p2m tables' Paul Durrant
2020-08-06 12:23 ` Jan Beulich
2020-08-14 7:12 ` Tian, Kevin
2020-08-04 13:42 ` [PATCH v4 12/14] vtd: use a bit field for root_entry Paul Durrant
2020-08-06 12:34 ` Jan Beulich
2020-08-12 13:13 ` Durrant, Paul
2020-08-18 8:27 ` Jan Beulich
2020-08-14 7:17 ` Tian, Kevin
2020-08-04 13:42 ` [PATCH v4 13/14] vtd: use a bit field for context_entry Paul Durrant
2020-08-06 12:46 ` Jan Beulich [this message]
2020-08-12 13:47 ` Paul Durrant
2020-08-14 7:19 ` Tian, Kevin
2020-08-04 13:42 ` [PATCH v4 14/14] vtd: use a bit field for dma_pte Paul Durrant
2020-08-06 12:53 ` Jan Beulich
2020-08-12 13:49 ` Paul Durrant
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