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irq/s390: Add arch_is_isolated_msi() for s390

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s390 doesn't use irq_domains, so it has no place to set
IRQ_DOMAIN_FLAG_ISOLATED_MSI. Instead of continuing to abuse the iommu
subsystem to convey this information add a simple define which s390 can
make statically true. The define will cause msi_device_has_isolated() to
return true.

Remove IOMMU_CAP_INTR_REMAP from the s390 iommu driver.

Link: https://lore.kernel.org/r/8-v3-3313bb5dd3a3+10f11-secure_msi_jgg@nvidia.com
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Jason Gunthorpe 2022-11-28 20:31:57 -04:00
parent f188bdb5f1
commit bf210f7939
4 changed files with 25 additions and 6 deletions
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17
arch/s390/include/asm/msi.h Normal file
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@ -0,0 +1,17 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_S390_MSI_H
#define _ASM_S390_MSI_H
#include <asm-generic/msi.h>
/*
* Work around S390 not using irq_domain at all so we can't set
* IRQ_DOMAIN_FLAG_ISOLATED_MSI. See for an explanation how it works:
*
* https://lore.kernel.org/r/31af8174-35e9-ebeb-b9ef-74c90d4bfd93@linux.ibm.com/
*
* Note this is less isolated than the ARM/x86 versions as userspace can trigger
* MSI belonging to kernel devices within the same gisa.
*/
#define arch_is_isolated_msi() true
#endif

2
drivers/iommu/s390-iommu.c
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@ -34,8 +34,6 @@ static bool s390_iommu_capable(struct device *dev, enum iommu_cap cap)
switch (cap) {
case IOMMU_CAP_CACHE_COHERENCY:
return true;
case IOMMU_CAP_INTR_REMAP:
return true;
default:
return false;
}

10
include/linux/msi.h
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@ -48,6 +48,10 @@ typedef struct arch_msi_msg_data {
} __attribute__ ((packed)) arch_msi_msg_data_t;
#endif
#ifndef arch_is_isolated_msi
#define arch_is_isolated_msi() false
#endif
/**
* msi_msg - Representation of a MSI message
* @address_lo: Low 32 bits of msi message address
@ -657,10 +661,10 @@ static inline bool msi_device_has_isolated_msi(struct device *dev)
/*
* Arguably if the platform does not enable MSI support then it has
* "isolated MSI", as an interrupt controller that cannot receive MSIs
* is inherently isolated by our definition. As nobody seems to needs
* this be conservative and return false anyhow.
* is inherently isolated by our definition. The default definition for
* arch_is_isolated_msi() is conservative and returns false anyhow.
*/
return false;
return arch_is_isolated_msi();
}
#endif /* CONFIG_GENERIC_MSI_IRQ */

2
kernel/irq/msi.c
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@ -1647,6 +1647,6 @@ bool msi_device_has_isolated_msi(struct device *dev)
for (; domain; domain = domain->parent)
if (domain->flags & IRQ_DOMAIN_FLAG_ISOLATED_MSI)
return true;
return false;
return arch_is_isolated_msi();
}
EXPORT_SYMBOL_GPL(msi_device_has_isolated_msi);