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From: Paolo Bonzini <pbonzini@redhat.com>
To: qemu-devel@nongnu.org
Subject: [PULL 26/26] scsi-generic: pass max_segments via max_iov field in BlockLimits
Date: Thu, 20 May 2021 10:22:57 +0200	[thread overview]
Message-ID: <20210520082257.187061-27-pbonzini@redhat.com> (raw)
In-Reply-To: <20210520082257.187061-1-pbonzini@redhat.com>

I/O to a disk via read/write is not limited by the number of segments allowed
by the host adapter; the kernel can split requests if needed, and the limit
imposed by the host adapter can be very low (256k or so) to avoid that SG_IO
returns EINVAL if memory is heavily fragmented.

Since this value is only interesting for SG_IO-based I/O, do not include
it in the max_transfer and only take it into account when patching the
block limits VPD page in the scsi-generic device.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/file-posix.c     | 3 +--
 hw/scsi/scsi-generic.c | 6 ++++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/block/file-posix.c b/block/file-posix.c
index 10b71d9a13..59c889d5a7 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1228,8 +1228,7 @@ static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
 
         ret = sg_get_max_segments(s->fd);
         if (ret > 0) {
-            bs->bl.max_transfer = MIN(bs->bl.max_transfer,
-                                      ret * qemu_real_host_page_size);
+            bs->bl.max_iov = ret;
         }
     }
 
diff --git a/hw/scsi/scsi-generic.c b/hw/scsi/scsi-generic.c
index 98c30c5d5c..82e1e2ee79 100644
--- a/hw/scsi/scsi-generic.c
+++ b/hw/scsi/scsi-generic.c
@@ -179,10 +179,12 @@ static void scsi_handle_inquiry_reply(SCSIGenericReq *r, SCSIDevice *s)
         (r->req.cmd.buf[1] & 0x01)) {
         page = r->req.cmd.buf[2];
         if (page == 0xb0) {
-            uint32_t max_transfer =
-                blk_get_max_transfer(s->conf.blk) / s->blocksize;
+            uint32_t max_transfer = blk_get_max_transfer(s->conf.blk);
+            uint32_t max_iov = blk_get_max_iov(s->conf.blk);
 
             assert(max_transfer);
+            max_transfer = MIN_NON_ZERO(max_transfer, max_iov * qemu_real_host_page_size)
+                / s->blocksize;
             stl_be_p(&r->buf[8], max_transfer);
             /* Also take care of the opt xfer len. */
             stl_be_p(&r->buf[12],
-- 
2.31.1



  parent reply	other threads:[~2021-05-20  8:40 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-20  8:22 [PULL 00/26] Misc patches for 2021-05-20 Paolo Bonzini
2021-05-20  8:22 ` [PULL 01/26] configure: Only clone softfloat-3 repositories if TCG is enabled Paolo Bonzini
2021-05-20  8:22 ` [PULL 02/26] configure: check for submodules if --with-git-submodules=ignore Paolo Bonzini
2021-05-20  8:22 ` [PULL 03/26] configure: simplify assignment to GIT_SUBMODULES Paolo Bonzini
2021-05-20  8:22 ` [PULL 04/26] hw/mem/nvdimm: Use Kconfig 'imply' instead of 'depends on' Paolo Bonzini
2021-05-20  8:22 ` [PULL 05/26] i386/cpu: Expose AVX_VNNI instruction to guest Paolo Bonzini
2021-05-20  8:22 ` [PULL 06/26] meson: bump submodule to 0.57.2 Paolo Bonzini
2021-05-20  8:22 ` [PULL 07/26] object: add more commands to preconfig mode Paolo Bonzini
2021-05-20  8:22 ` [PULL 08/26] qtest: add a QOM object for qtest Paolo Bonzini
2021-05-20  8:22 ` [PULL 09/26] KVM: do not allow setting properties at runtime Paolo Bonzini
2021-05-20  8:22 ` [PULL 10/26] memory: Introduce log_sync_global() to memory listener Paolo Bonzini
2021-05-20  8:22 ` [PULL 11/26] KVM: Use a big lock to replace per-kml slots_lock Paolo Bonzini
2021-05-20  8:22 ` [PULL 12/26] KVM: Create the KVMSlot dirty bitmap on flag changes Paolo Bonzini
2021-05-20  8:22 ` [PULL 13/26] KVM: Provide helper to get kvm dirty log Paolo Bonzini
2021-05-20  8:22 ` [PULL 14/26] KVM: Provide helper to sync dirty bitmap from slot to ramblock Paolo Bonzini
2021-05-20  8:22 ` [PULL 15/26] KVM: Simplify dirty log sync in kvm_set_phys_mem Paolo Bonzini
2021-05-20  8:22 ` [PULL 16/26] KVM: Cache kvm slot dirty bitmap size Paolo Bonzini
2021-05-20  8:22 ` [PULL 17/26] KVM: Add dirty-ring-size property Paolo Bonzini
2021-05-20  8:22 ` [PULL 18/26] KVM: Disable manual dirty log when dirty ring enabled Paolo Bonzini
2021-05-20  8:22 ` [PULL 19/26] KVM: Dirty ring support Paolo Bonzini
2021-05-20  8:22 ` [PULL 20/26] tests/qtest/fuzz: Fix build failure Paolo Bonzini
2021-05-20  8:22 ` [PULL 21/26] meson: Set implicit_include_directories to false Paolo Bonzini
2021-05-20  8:22 ` [PULL 22/26] remove qemu-options* from root directory Paolo Bonzini
2021-05-20  8:22 ` [PULL 23/26] replication: move include out of " Paolo Bonzini
2021-05-20  8:22 ` [PULL 24/26] vl: allow not specifying size in -m when using -M memory-backend Paolo Bonzini
2021-05-20  8:22 ` [PULL 25/26] qemu-config: load modules when instantiating option groups Paolo Bonzini
2021-05-20  8:22 ` Paolo Bonzini [this message]
2021-05-20  8:54 ` [PULL 00/26] Misc patches for 2021-05-20 no-reply
2021-05-20 13:26 ` Peter Maydell
2021-05-20 14:20   ` Peter Maydell
2021-05-20 14:25     ` Peter Maydell
2021-05-21 13:27   ` Paolo Bonzini
2021-05-21 13:44     ` Peter Maydell
2021-05-24  9:42       ` Paolo Bonzini

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