Commit 57cdb720 authored by Suravee Suthikulpanit's avatar Suravee Suthikulpanit Committed by Joerg Roedel
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iommu/amd: Do not flush IRTE when only updating isRun and destination fields 

According to the recent update in the AMD IOMMU spec [1], the IsRun and
Destination fields of the Interrupt Remapping Table Entry (IRTE) are not
cached by the IOMMU hardware.

Therefore, do not issue the INVALIDATE_INTERRUPT_TABLE command when
updating IRTE[IsRun] and IRTE[Destination] when IRTE[GuestMode]=1, which
should help improve IOMMU AVIC/x2AVIC performance.

References:
[1] AMD IOMMU Spec Revision (Rev 3.08-PUB)
(Link: https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/specifications/48882_IOMMU.pdf

)

Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Signed-off-by: default avatarSuravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Reviewed-by: default avatarVasant Hegde <vasant.hegde@amd.com>
Tested-by: default avatarAlejandro Jimenez <alejandro.j.jimenez@oracle.com>
Link: https://lore.kernel.org/r/20231017144236.8287-1-suravee.suthikulpanit@amd.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 9abe6c55

drivers/iommu/amd/iommu.c

+16 −4
Original line number Diff line number Diff line
@@ -3111,7 +3111,7 @@ static int alloc_irq_index(struct amd_iommu *iommu, u16 devid, int count, 
	return index;

}



static int modify_irte_ga(struct amd_iommu *iommu, u16 devid, int index,

static int __modify_irte_ga(struct amd_iommu *iommu, u16 devid, int index,

			    struct irte_ga *irte)

{

	struct irq_remap_table *table;
@@ -3139,6 +3139,18 @@ static int modify_irte_ga(struct amd_iommu *iommu, u16 devid, int index, 


	raw_spin_unlock_irqrestore(&table->lock, flags);



	return 0;

}



static int modify_irte_ga(struct amd_iommu *iommu, u16 devid, int index,

			  struct irte_ga *irte)

{

	bool ret;



	ret = __modify_irte_ga(iommu, devid, index, irte);

	if (ret)

		return ret;



	iommu_flush_irt_and_complete(iommu, devid);



	return 0;
@@ -3822,7 +3834,7 @@ int amd_iommu_update_ga(int cpu, bool is_run, void *data) 
	}

	entry->lo.fields_vapic.is_run = is_run;



	return modify_irte_ga(ir_data->iommu, ir_data->irq_2_irte.devid,

	return __modify_irte_ga(ir_data->iommu, ir_data->irq_2_irte.devid,

				ir_data->irq_2_irte.index, entry);

}

EXPORT_SYMBOL(amd_iommu_update_ga);