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Message-ID: <56C5E450.3010501@linaro.org>
Date: Thu, 18 Feb 2016 16:33:36 +0100
From: Eric Auger <eric.auger@...aro.org>
To: Marc Zyngier <marc.zyngier@....com>, leo.duran@....com
Cc: eric.auger@...com, alex.williamson@...hat.com, will.deacon@....com,
joro@...tes.org, tglx@...utronix.de, jason@...edaemon.net,
christoffer.dall@...aro.org, linux-arm-kernel@...ts.infradead.org,
kvmarm@...ts.cs.columbia.edu, kvm@...r.kernel.org,
suravee.suthikulpanit@....com, patches@...aro.org,
linux-kernel@...r.kernel.org, Manish.Jaggi@...iumnetworks.com,
Bharat.Bhushan@...escale.com, pranav.sawargaonkar@...il.com,
p.fedin@...sung.com, iommu@...ts.linux-foundation.org,
sherry.hurwitz@....com, brijesh.singh@....com,
Thomas.Lendacky@....com
Subject: Re: [RFC v3 15/15] irqchip/gicv2m/v3-its-pci-msi: IOMMU map the MSI
frame when needed
Hi Marc,
On 02/18/2016 12:33 PM, Marc Zyngier wrote:
> On Fri, 12 Feb 2016 08:13:17 +0000
> Eric Auger <eric.auger@...aro.org> wrote:
>
>> In case the msi_desc references a device attached to an iommu
>> domain, the msi address needs to be mapped in the IOMMU. Else any
>> MSI write transaction will cause a fault.
>>
>> gic_set_msi_addr detects that case and allocates an iova bound
>> to the physical address page comprising the MSI frame. This iova
>> then is used as the msi_msg address. Unset operation decrements the
>> reference on the binding.
>>
>> The functions are called in the irq_write_msi_msg ops implementation.
>> At that time we can recognize whether the msi is setup or teared down
>> looking at the msi_msg content. Indeed msi_domain_deactivate zeroes all
>> the fields.
>>
>> Signed-off-by: Eric Auger <eric.auger@...aro.org>
>>
>> ---
>>
>> v2 -> v3:
>> - protect iova/addr manipulation with CONFIG_ARCH_DMA_ADDR_T_64BIT and
>> CONFIG_PHYS_ADDR_T_64BIT
>> - only expose gic_pci_msi_domain_write_msg in case CONFIG_IOMMU_API &
>> CONFIG_PCI_MSI_IRQ_DOMAIN are set.
>> - gic_set/unset_msi_addr duly become static
>> ---
>> drivers/irqchip/irq-gic-common.c | 69 ++++++++++++++++++++++++++++++++
>> drivers/irqchip/irq-gic-common.h | 5 +++
>> drivers/irqchip/irq-gic-v2m.c | 7 +++-
>> drivers/irqchip/irq-gic-v3-its-pci-msi.c | 5 +++
>> 4 files changed, 85 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/irqchip/irq-gic-common.c b/drivers/irqchip/irq-gic-common.c
>> index f174ce0..46cd06c 100644
>> --- a/drivers/irqchip/irq-gic-common.c
>> +++ b/drivers/irqchip/irq-gic-common.c
>> @@ -18,6 +18,8 @@
>> #include <linux/io.h>
>> #include <linux/irq.h>
>> #include <linux/irqchip/arm-gic.h>
>> +#include <linux/iommu.h>
>> +#include <linux/msi.h>
>>
>> #include "irq-gic-common.h"
>>
>> @@ -121,3 +123,70 @@ void gic_cpu_config(void __iomem *base, void (*sync_access)(void))
>> if (sync_access)
>> sync_access();
>> }
>> +
>> +#if defined(CONFIG_IOMMU_API) && defined(CONFIG_PCI_MSI_IRQ_DOMAIN)
>> +static int gic_set_msi_addr(struct irq_data *data, struct msi_msg *msg)
>> +{
>> + struct msi_desc *desc = irq_data_get_msi_desc(data);
>> + struct device *dev = msi_desc_to_dev(desc);
>> + struct iommu_domain *d;
>> + phys_addr_t addr;
>> + dma_addr_t iova;
>> + int ret;
>> +
>> + d = iommu_get_domain_for_dev(dev);
>> + if (!d)
>> + return 0;
>> +#ifdef CONFIG_PHYS_ADDR_T_64BIT
>> + addr = ((phys_addr_t)(msg->address_hi) << 32) | msg->address_lo;
>> +#else
>> + addr = msg->address_lo;
>> +#endif
>> +
>> + ret = iommu_get_single_reserved(d, addr, IOMMU_WRITE, &iova);
>> +
>> + if (!ret) {
>> + msg->address_lo = lower_32_bits(iova);
>> + msg->address_hi = upper_32_bits(iova);
>> + }
>> + return ret;
>> +}
>> +
>> +
>> +static void gic_unset_msi_addr(struct irq_data *data)
>> +{
>> + struct msi_desc *desc = irq_data_get_msi_desc(data);
>> + struct device *dev;
>> + struct iommu_domain *d;
>> + dma_addr_t iova;
>> +
>> +#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
>> + iova = ((dma_addr_t)(desc->msg.address_hi) << 32) |
>> + desc->msg.address_lo;
>> +#else
>> + iova = desc->msg.address_lo;
>> +#endif
>> +
>> + dev = msi_desc_to_dev(desc);
>> + if (!dev)
>> + return;
>> +
>> + d = iommu_get_domain_for_dev(dev);
>> + if (!d)
>> + return;
>> +
>> + iommu_put_single_reserved(d, iova);
>> +}
>> +
>> +void gic_pci_msi_domain_write_msg(struct irq_data *irq_data,
>> + struct msi_msg *msg)
>> +{
>> + if (!msg->address_hi && !msg->address_lo && !msg->data)
>> + gic_unset_msi_addr(irq_data); /* deactivate */
>> + else
>> + gic_set_msi_addr(irq_data, msg); /* activate, set_affinity */
>> +
>> + pci_msi_domain_write_msg(irq_data, msg);
>> +}
>
> So by doing that, you are specializing this infrastructure to PCI.
> If you hijacked irq_compose_msi_msg() instead, you'd have both
> platform and PCI MSI for the same price.
>
> I can see a potential problem with the teardown of an MSI (I don't
> think the compose method is called on teardown), but I think this could
> be easily addressed.
Yes effectively this is the reason why I moved it from
irq_compose_msi_msg (my original implementation) to irq_write_msi_msg. I
noticed I had no way to detect the teardown whereas the
msi_domain_deactivate also calls irq_write_msi_msg which is quite
practical ;-) To be honest I need to further look at the non PCI
implementation.
>
>> +#endif
>> +
>> diff --git a/drivers/irqchip/irq-gic-common.h b/drivers/irqchip/irq-gic-common.h
>> index fff697d..98681fd 100644
>> --- a/drivers/irqchip/irq-gic-common.h
>> +++ b/drivers/irqchip/irq-gic-common.h
>> @@ -35,4 +35,9 @@ void gic_cpu_config(void __iomem *base, void (*sync_access)(void));
>> void gic_enable_quirks(u32 iidr, const struct gic_quirk *quirks,
>> void *data);
>>
>> +#if defined(CONFIG_PCI_MSI_IRQ_DOMAIN) && defined(CONFIG_IOMMU_API)
>> +void gic_pci_msi_domain_write_msg(struct irq_data *irq_data,
>> + struct msi_msg *msg);
>> +#endif
>> +
>> #endif /* _IRQ_GIC_COMMON_H */
>> diff --git a/drivers/irqchip/irq-gic-v2m.c b/drivers/irqchip/irq-gic-v2m.c
>> index c779f83..692d809 100644
>> --- a/drivers/irqchip/irq-gic-v2m.c
>> +++ b/drivers/irqchip/irq-gic-v2m.c
>> @@ -24,6 +24,7 @@
>> #include <linux/of_pci.h>
>> #include <linux/slab.h>
>> #include <linux/spinlock.h>
>> +#include "irq-gic-common.h"
>>
>> /*
>> * MSI_TYPER:
>> @@ -83,7 +84,11 @@ static struct irq_chip gicv2m_msi_irq_chip = {
>> .irq_mask = gicv2m_mask_msi_irq,
>> .irq_unmask = gicv2m_unmask_msi_irq,
>> .irq_eoi = irq_chip_eoi_parent,
>> - .irq_write_msi_msg = pci_msi_domain_write_msg,
>> +#ifdef CONFIG_IOMMU_API
>> + .irq_write_msi_msg = gic_pci_msi_domain_write_msg,
>> +#else
>> + .irq_write_msi_msg = pci_msi_domain_write_msg,
>> +#endif
>
> Irrespective of the way you implement the translation procedure, you
> should make this unconditional, and have the #ifdefery in the code that
> implements it.
OK
Thanks
Eric
>
>> };
>>
>> static struct msi_domain_info gicv2m_msi_domain_info = {
>> diff --git a/drivers/irqchip/irq-gic-v3-its-pci-msi.c b/drivers/irqchip/irq-gic-v3-its-pci-msi.c
>> index 8223765..690504e 100644
>> --- a/drivers/irqchip/irq-gic-v3-its-pci-msi.c
>> +++ b/drivers/irqchip/irq-gic-v3-its-pci-msi.c
>> @@ -19,6 +19,7 @@
>> #include <linux/of.h>
>> #include <linux/of_irq.h>
>> #include <linux/of_pci.h>
>> +#include "irq-gic-common.h"
>>
>> static void its_mask_msi_irq(struct irq_data *d)
>> {
>> @@ -37,7 +38,11 @@ static struct irq_chip its_msi_irq_chip = {
>> .irq_unmask = its_unmask_msi_irq,
>> .irq_mask = its_mask_msi_irq,
>> .irq_eoi = irq_chip_eoi_parent,
>> +#ifdef CONFIG_IOMMU_API
>> + .irq_write_msi_msg = gic_pci_msi_domain_write_msg,
>> +#else
>> .irq_write_msi_msg = pci_msi_domain_write_msg,
>> +#endif
>> };
>>
>> struct its_pci_alias {
>
> Thanks,
>
> M.
>
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