d0596f4f1e
- kvm-monitor-generalize-query-mshv-info-mshv-to-query-acc.patch [RHEL-134212] - kvm-block-Improve-comments-in-BlockLimits.patch [RHEL-110003] - kvm-block-Expose-block-limits-for-images-in-QMP.patch [RHEL-110003] - kvm-qemu-img-info-Optionally-show-block-limits.patch [RHEL-110003] - kvm-qemu-img-info-Add-cache-mode-option.patch [RHEL-110003] - kvm-rh-configs-enable-CONFIG_TDX-for-x86_64.patch [RHEL-111853] - Resolves: RHEL-134212 ([RHEL10.2] L1VH qemu downstream initial merge RHEL10.2) - Resolves: RHEL-110003 (Expose block limits of block nodes in QMP and qemu-img) - Resolves: RHEL-111853 ([Intel 10.0 FEAT] [SPR] TDX: Virt-QEMU: QEMU Support [rhel-10])
99 lines
3.9 KiB
Diff
99 lines
3.9 KiB
Diff
From e5745092ebc473f359cb2eef67ff375a1e942a74 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Fri, 24 Oct 2025 14:30:37 +0200
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Subject: [PATCH 2/6] block: Improve comments in BlockLimits
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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RH-MergeRequest: 439: block: Expose block limits in monitor and qemu-img info
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RH-Jira: RHEL-110003
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RH-Acked-by: Hanna Czenczek <hreitz@redhat.com>
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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RH-Commit: [1/4] 06c55e52ff339d2bc4559b109b0a6dd625caa7f0 (kmwolf/centos-qemu-kvm)
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Patches to expose the limits in QAPI have made clear that the existing
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documentation of BlockLimits could be improved: The meaning of
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min_mem_alignment and opt_mem_alignment could be clearer, and talking
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about better alignment values isn't helpful when we only detect these
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values and never choose them.
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Make the changes in the BlockLimits documentation now, so that the
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patches exposing the fields in QAPI can use descriptions consistent with
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it.
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Message-ID: <20251024123041.51254-2-kwolf@redhat.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit 46dd683d56b1328cb2bc923914bfd7ac590064f7)
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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---
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include/block/block_int-common.h | 30 +++++++++++++++++-------------
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1 file changed, 17 insertions(+), 13 deletions(-)
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diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
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index 034c0634c8..5206f32d53 100644
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--- a/include/block/block_int-common.h
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+++ b/include/block/block_int-common.h
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@@ -817,10 +817,10 @@ typedef struct BlockLimits {
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int64_t max_pdiscard;
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/*
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- * Optimal alignment for discard requests in bytes. A power of 2
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- * is best but not mandatory. Must be a multiple of
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- * bl.request_alignment, and must be less than max_pdiscard if
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- * that is set. May be 0 if bl.request_alignment is good enough
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+ * Optimal alignment for discard requests in bytes. Note that this doesn't
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+ * have to be a power of two. Must be a multiple of bl.request_alignment,
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+ * and must be less than max_pdiscard if that is set. May be 0 if
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+ * bl.request_alignment is good enough.
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*/
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uint32_t pdiscard_alignment;
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@@ -831,11 +831,10 @@ typedef struct BlockLimits {
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int64_t max_pwrite_zeroes;
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/*
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- * Optimal alignment for write zeroes requests in bytes. A power
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- * of 2 is best but not mandatory. Must be a multiple of
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- * bl.request_alignment, and must be less than max_pwrite_zeroes
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- * if that is set. May be 0 if bl.request_alignment is good
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- * enough
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+ * Optimal alignment for write zeroes requests in bytes. Note that this
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+ * doesn't have to be a power of two. Must be a multiple of
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+ * bl.request_alignment, and must be less than max_pwrite_zeroes if that is
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+ * set. May be 0 if bl.request_alignment is good enough.
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*/
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uint32_t pwrite_zeroes_alignment;
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@@ -863,18 +862,23 @@ typedef struct BlockLimits {
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uint64_t max_hw_transfer;
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/*
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- * Maximal number of scatter/gather elements allowed by the hardware.
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+ * Maximum number of scatter/gather elements allowed by the hardware.
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* Applies whenever transfers to the device bypass the kernel I/O
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* scheduler, for example with SG_IO. If larger than max_iov
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* or if zero, blk_get_max_hw_iov will fall back to max_iov.
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*/
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int max_hw_iov;
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-
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- /* memory alignment, in bytes so that no bounce buffer is needed */
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+ /*
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+ * Minimal required memory alignment in bytes for zero-copy I/O to succeed.
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+ * For unaligned requests, a bounce buffer will be used.
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+ */
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size_t min_mem_alignment;
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- /* memory alignment, in bytes, for bounce buffer */
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+ /*
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+ * Optimal memory alignment in bytes. This is the alignment used for any
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+ * buffer allocations QEMU performs internally.
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+ */
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size_t opt_mem_alignment;
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/* maximum number of iovec elements */
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--
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2.47.3
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