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List: xen-cvs
Subject: [Xen-changelog] [xen master] x86/vMSI-X: avoid missing first unmask of vectors
From: patchbot () xen ! org
Date: 2016-04-27 18:11:02
Message-ID: E1avTvS-0006kG-Ly () xenbits ! xenproject ! org
[Download RAW message or body]
commit 3a6222bd57209d4c2f098d61ace042370a9b0a96
Author: Jan Beulich <jbeulich@suse.com>
AuthorDate: Tue Apr 26 11:52:22 2016 +0200
Commit: Jan Beulich <jbeulich@suse.com>
CommitDate: Tue Apr 26 11:52:22 2016 +0200
x86/vMSI-X: avoid missing first unmask of vectors
Recent changes to Linux result in there just being a single unmask
operation prior to expecting the first interrupts to arrive. However,
we've had a chicken-and-egg problem here: Qemu invokes
xc_domain_update_msi_irq(), ultimately leading to
msixtbl_pt_register(), upon seeing that first unmask operation. Yet
for msixtbl_range() to return true (in order to msixtbl_write() to get
invoked at all) msixtbl_pt_register() must have completed.
Deal with this by snooping suitable writes in msixtbl_range() and
triggering the invocation of msix_write_completion() from
msixtbl_pt_register() when that happens in the context of a still in
progress vector control field write.
Note that the seemingly unrelated deletion of the redundant
irq_desc->msi_desc check in msixtbl_pt_register() is to make clear to
any compiler version used that the "msi_desc" local variable isn't
being used uninitialized. (Doing the same in msixtbl_pt_unregister() is
just for consistency reasons.)
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
---
xen/arch/x86/hvm/vmsi.c | 40 +++++++++++++++++++++++++++++++++-------
xen/include/asm-x86/hvm/vcpu.h | 1 +
2 files changed, 34 insertions(+), 7 deletions(-)
diff --git a/xen/arch/x86/hvm/vmsi.c b/xen/arch/x86/hvm/vmsi.c
index d450a3c..805e560 100644
--- a/xen/arch/x86/hvm/vmsi.c
+++ b/xen/arch/x86/hvm/vmsi.c
@@ -341,7 +341,21 @@ static int msixtbl_range(struct vcpu *v, unsigned long addr)
desc = msixtbl_addr_to_desc(msixtbl_find_entry(v, addr), addr);
rcu_read_unlock(&msixtbl_rcu_lock);
- return !!desc;
+ if ( desc )
+ return 1;
+
+ if ( (addr & (PCI_MSIX_ENTRY_SIZE - 1)) ==
+ PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET )
+ {
+ const ioreq_t *r = &v->arch.hvm_vcpu.hvm_io.io_req;
+
+ ASSERT(r->type == IOREQ_TYPE_COPY);
+ if ( r->dir == IOREQ_WRITE && r->size == 4 && !r->data_is_ptr
+ && !(r->data & PCI_MSIX_VECTOR_BITMASK) )
+ v->arch.hvm_vcpu.hvm_io.msix_snoop_address = addr;
+ }
+
+ return 0;
}
static const struct hvm_mmio_ops msixtbl_mmio_ops = {
@@ -410,9 +424,6 @@ int msixtbl_pt_register(struct domain *d, struct pirq *pirq, uint64_t gtable)
return r;
}
- if ( !irq_desc->msi_desc )
- goto out;
-
msi_desc = irq_desc->msi_desc;
if ( !msi_desc )
goto out;
@@ -437,6 +448,22 @@ found:
out:
spin_unlock_irq(&irq_desc->lock);
xfree(new_entry);
+
+ if ( !r )
+ {
+ struct vcpu *v;
+
+ for_each_vcpu ( d, v )
+ {
+ if ( v->arch.hvm_vcpu.hvm_io.msix_snoop_address ==
+ (gtable + msi_desc->msi_attrib.entry_nr *
+ PCI_MSIX_ENTRY_SIZE +
+ PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET) )
+ v->arch.hvm_vcpu.hvm_io.msix_unmask_address =
+ v->arch.hvm_vcpu.hvm_io.msix_snoop_address;
+ }
+ }
+
return r;
}
@@ -457,9 +484,6 @@ void msixtbl_pt_unregister(struct domain *d, struct pirq *pirq)
if ( !irq_desc )
return;
- if ( !irq_desc->msi_desc )
- goto out;
-
msi_desc = irq_desc->msi_desc;
if ( !msi_desc )
goto out;
@@ -522,6 +546,8 @@ void msix_write_completion(struct vcpu *v)
{
unsigned long ctrl_address = v->arch.hvm_vcpu.hvm_io.msix_unmask_address;
+ v->arch.hvm_vcpu.hvm_io.msix_snoop_address = 0;
+
if ( !ctrl_address )
return;
diff --git a/xen/include/asm-x86/hvm/vcpu.h b/xen/include/asm-x86/hvm/vcpu.h
index 152d9f3..06778eb 100644
--- a/xen/include/asm-x86/hvm/vcpu.h
+++ b/xen/include/asm-x86/hvm/vcpu.h
@@ -85,6 +85,7 @@ struct hvm_vcpu_io {
bool_t mmio_retry;
unsigned long msix_unmask_address;
+ unsigned long msix_snoop_address;
const struct g2m_ioport *g2m_ioport;
};
--
generated by git-patchbot for /home/xen/git/xen.git#master
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