linux-kernel - Re: [PATCH v2] PCI: hv: Fix the definition of vector in hv_compose_msi

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Date:   Wed, 29 Mar 2023 19:55:32 -0700
From:   Boqun Feng <boqun.feng@...il.com>
To:     Dexuan Cui <decui@...rosoft.com>
Cc:     quic_jhugo@...cinc.com, quic_carlv@...cinc.com, wei.liu@...nel.org,
        kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        lpieralisi@...nel.org, bhelgaas@...gle.com,
        linux-hyperv@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, mikelley@...rosoft.com,
        robh@...nel.org, kw@...ux.com, helgaas@...nel.org,
        alex.williamson@...hat.com, stable@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH v2] PCI: hv: Fix the definition of vector in
 hv_compose_msi_msg()

On Wed, Mar 29, 2023 at 06:56:12PM -0700, Boqun Feng wrote:
> [Cc stable]
> 
> On Thu, Oct 27, 2022 at 01:52:56PM -0700, Dexuan Cui wrote:
> > The local variable 'vector' must be u32 rather than u8: see the
> > struct hv_msi_desc3.
> > 
> > 'vector_count' should be u16 rather than u8: see struct hv_msi_desc,
> > hv_msi_desc2 and hv_msi_desc3.
> > 
> 
> Dexuan, I think this patch should only be in 5.15, because...
> 

Sorry, I meant:

"this patch should also be backported in 5.15"

Regards,
Boqun

> > Fixes: a2bad844a67b ("PCI: hv: Fix interrupt mapping for multi-MSI")
> 
> ^^^ this commit is already in 5.15.y (commit id 92dcb50f7f09).
> 
> Upstream id e70af8d040d2b7904dca93d942ba23fb722e21b1
> Cc: <stable@...r.kernel.org> # 5.15.x
> 
> Regards,
> Boqun
> 
> > Signed-off-by: Dexuan Cui <decui@...rosoft.com>
> > Cc: Jeffrey Hugo <quic_jhugo@...cinc.com>
> > Cc: Carl Vanderlip <quic_carlv@...cinc.com>
> > ---
> > 
> > v1 was posted here (sorry, I forgot to follow this up...):
> > https://lwn.net/ml/linux-kernel/20220815185505.7626-1-decui@microsoft.com/
> > 
> > Changes in v2:
> >   Added the explicit "(u8)" cast in hv_compose_msi_msg().
> >   Added and improved the comments.
> >   Fixed a typo in the subject in v1: s/definiton/definition
> > 
> >  drivers/pci/controller/pci-hyperv.c | 22 ++++++++++++++++------
> >  1 file changed, 16 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> > index e7c6f6629e7c..ba64284eaf9f 100644
> > --- a/drivers/pci/controller/pci-hyperv.c
> > +++ b/drivers/pci/controller/pci-hyperv.c
> > @@ -1614,7 +1614,7 @@ static void hv_pci_compose_compl(void *context, struct pci_response *resp,
> >  
> >  static u32 hv_compose_msi_req_v1(
> >  	struct pci_create_interrupt *int_pkt, const struct cpumask *affinity,
> > -	u32 slot, u8 vector, u8 vector_count)
> > +	u32 slot, u8 vector, u16 vector_count)
> >  {
> >  	int_pkt->message_type.type = PCI_CREATE_INTERRUPT_MESSAGE;
> >  	int_pkt->wslot.slot = slot;
> > @@ -1642,7 +1642,7 @@ static int hv_compose_msi_req_get_cpu(const struct cpumask *affinity)
> >  
> >  static u32 hv_compose_msi_req_v2(
> >  	struct pci_create_interrupt2 *int_pkt, const struct cpumask *affinity,
> > -	u32 slot, u8 vector, u8 vector_count)
> > +	u32 slot, u8 vector, u16 vector_count)
> >  {
> >  	int cpu;
> >  
> > @@ -1661,7 +1661,7 @@ static u32 hv_compose_msi_req_v2(
> >  
> >  static u32 hv_compose_msi_req_v3(
> >  	struct pci_create_interrupt3 *int_pkt, const struct cpumask *affinity,
> > -	u32 slot, u32 vector, u8 vector_count)
> > +	u32 slot, u32 vector, u16 vector_count)
> >  {
> >  	int cpu;
> >  
> > @@ -1701,7 +1701,12 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> >  	struct compose_comp_ctxt comp;
> >  	struct tran_int_desc *int_desc;
> >  	struct msi_desc *msi_desc;
> > -	u8 vector, vector_count;
> > +	/*
> > +	 * vector_count should be u16: see hv_msi_desc, hv_msi_desc2
> > +	 * and hv_msi_desc3. vector must be u32: see hv_msi_desc3.
> > +	 */
> > +	u16 vector_count;
> > +	u32 vector;
> >  	struct {
> >  		struct pci_packet pci_pkt;
> >  		union {
> > @@ -1767,6 +1772,11 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> >  		vector_count = 1;
> >  	}
> >  
> > +	/*
> > +	 * hv_compose_msi_req_v1 and v2 are for x86 only, meaning 'vector'
> > +	 * can't exceed u8. Cast 'vector' down to u8 for v1/v2 explicitly
> > +	 * for better readability.
> > +	 */
> >  	memset(&ctxt, 0, sizeof(ctxt));
> >  	init_completion(&comp.comp_pkt.host_event);
> >  	ctxt.pci_pkt.completion_func = hv_pci_compose_compl;
> > @@ -1777,7 +1787,7 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> >  		size = hv_compose_msi_req_v1(&ctxt.int_pkts.v1,
> >  					dest,
> >  					hpdev->desc.win_slot.slot,
> > -					vector,
> > +					(u8)vector,
> >  					vector_count);
> >  		break;
> >  
> > @@ -1786,7 +1796,7 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> >  		size = hv_compose_msi_req_v2(&ctxt.int_pkts.v2,
> >  					dest,
> >  					hpdev->desc.win_slot.slot,
> > -					vector,
> > +					(u8)vector,
> >  					vector_count);
> >  		break;
> >  
> > -- 
> > 2.25.1
> >