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Message-ID: <6472fa11-09f4-3e0f-dbec-cf76bcf342c4@linux.ibm.com>
Date: Tue, 14 Dec 2021 13:13:11 -0500
From: Matthew Rosato <mjrosato@...ux.ibm.com>
To: Pierre Morel <pmorel@...ux.ibm.com>, linux-s390@...r.kernel.org
Cc: alex.williamson@...hat.com, cohuck@...hat.com,
schnelle@...ux.ibm.com, farman@...ux.ibm.com,
borntraeger@...ux.ibm.com, hca@...ux.ibm.com, gor@...ux.ibm.com,
gerald.schaefer@...ux.ibm.com, agordeev@...ux.ibm.com,
frankja@...ux.ibm.com, david@...hat.com, imbrenda@...ux.ibm.com,
vneethv@...ux.ibm.com, oberpar@...ux.ibm.com, freude@...ux.ibm.com,
thuth@...hat.com, pasic@...ux.ibm.com, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 22/32] KVM: s390: pci: provide routines for
enabling/disabling IOAT assist
On 12/14/21 12:46 PM, Pierre Morel wrote:
>
>
> On 12/7/21 21:57, Matthew Rosato wrote:
>> These routines will be wired into the vfio_pci_zdev ioctl handlers to
>> respond to requests to enable / disable a device for PCI I/O Address
>> Translation assistance.
>>
>> Signed-off-by: Matthew Rosato <mjrosato@...ux.ibm.com>
>> ---
>> arch/s390/include/asm/kvm_pci.h | 15 ++++
>> arch/s390/include/asm/pci_dma.h | 2 +
>> arch/s390/kvm/pci.c | 133 ++++++++++++++++++++++++++++++++
>> arch/s390/kvm/pci.h | 2 +
>> 4 files changed, 152 insertions(+)
>>
>> diff --git a/arch/s390/include/asm/kvm_pci.h
>> b/arch/s390/include/asm/kvm_pci.h
>> index 54a0afdbe7d0..254275399f21 100644
>> --- a/arch/s390/include/asm/kvm_pci.h
>> +++ b/arch/s390/include/asm/kvm_pci.h
>> @@ -16,11 +16,21 @@
>> #include <linux/kvm_host.h>
>> #include <linux/kvm.h>
>> #include <linux/pci.h>
>> +#include <linux/mutex.h>
>> #include <asm/pci_insn.h>
>> +#include <asm/pci_dma.h>
>> +
>> +struct kvm_zdev_ioat {
>> + unsigned long *head[ZPCI_TABLE_PAGES];
>> + unsigned long **seg;
>> + unsigned long ***pt;
>> + struct mutex lock;
>> +};
>> struct kvm_zdev {
>> struct zpci_dev *zdev;
>> struct kvm *kvm;
>> + struct kvm_zdev_ioat ioat;
>> struct zpci_fib fib;
>> };
>> @@ -33,6 +43,11 @@ extern int kvm_s390_pci_aif_enable(struct zpci_dev
>> *zdev, struct zpci_fib *fib,
>> bool assist);
>> extern int kvm_s390_pci_aif_disable(struct zpci_dev *zdev);
>> +extern int kvm_s390_pci_ioat_probe(struct zpci_dev *zdev);
>> +extern int kvm_s390_pci_ioat_enable(struct zpci_dev *zdev, u64 iota);
>> +extern int kvm_s390_pci_ioat_disable(struct zpci_dev *zdev);
>> +extern u8 kvm_s390_pci_get_dtsm(struct zpci_dev *zdev);
>> +
>> extern int kvm_s390_pci_interp_probe(struct zpci_dev *zdev);
>> extern int kvm_s390_pci_interp_enable(struct zpci_dev *zdev);
>> extern int kvm_s390_pci_interp_disable(struct zpci_dev *zdev);
>> diff --git a/arch/s390/include/asm/pci_dma.h
>> b/arch/s390/include/asm/pci_dma.h
>> index 3b8e89d4578a..e1d3c1d3fc8a 100644
>> --- a/arch/s390/include/asm/pci_dma.h
>> +++ b/arch/s390/include/asm/pci_dma.h
>> @@ -50,6 +50,8 @@ enum zpci_ioat_dtype {
>> #define ZPCI_TABLE_ALIGN ZPCI_TABLE_SIZE
>> #define ZPCI_TABLE_ENTRY_SIZE (sizeof(unsigned long))
>> #define ZPCI_TABLE_ENTRIES (ZPCI_TABLE_SIZE /
>> ZPCI_TABLE_ENTRY_SIZE)
>> +#define ZPCI_TABLE_PAGES (ZPCI_TABLE_SIZE >> PAGE_SHIFT)
>> +#define ZPCI_TABLE_ENTRIES_PAGES (ZPCI_TABLE_ENTRIES *
>> ZPCI_TABLE_PAGES)
>> #define ZPCI_TABLE_BITS 11
>> #define ZPCI_PT_BITS 8
>> diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
>> index 3a29398dd53b..a1c0c0881332 100644
>> --- a/arch/s390/kvm/pci.c
>> +++ b/arch/s390/kvm/pci.c
>> @@ -12,6 +12,7 @@
>> #include <asm/kvm_pci.h>
>> #include <asm/pci.h>
>> #include <asm/pci_insn.h>
>> +#include <asm/pci_dma.h>
>> #include <asm/sclp.h>
>> #include "pci.h"
>> #include "kvm-s390.h"
>> @@ -315,6 +316,131 @@ int kvm_s390_pci_aif_disable(struct zpci_dev *zdev)
>> }
>> EXPORT_SYMBOL_GPL(kvm_s390_pci_aif_disable);
>> +int kvm_s390_pci_ioat_probe(struct zpci_dev *zdev)
>> +{
>> + return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(kvm_s390_pci_ioat_probe);
>> +
>> +int kvm_s390_pci_ioat_enable(struct zpci_dev *zdev, u64 iota)
>> +{
>> + gpa_t gpa = (gpa_t)(iota & ZPCI_RTE_ADDR_MASK);
>> + struct kvm_zdev_ioat *ioat;
>> + struct page *page;
>> + struct kvm *kvm;
>> + unsigned int idx;
>> + void *iaddr;
>> + int i, rc = 0;
>> +
>> + if (!zdev->kzdev || !zdev->kzdev->kvm || zdev->kzdev->ioat.head[0])
>> + return -EINVAL;
>
> The only caller already checked zdev->kzdev.
I tend to get overzealous with these checks..
> Could we use a macro to replace zdev->kzdev->ioat.head[0] ?
> like
> #define shadow_pgtbl_initialized zdev->kzdev->ioat.head[0] >
> Would be clearer for me.
Sure
>
>> +
>> + /* Ensure supported type specified */
>> + if ((iota & ZPCI_IOTA_RTTO_FLAG) != ZPCI_IOTA_RTTO_FLAG)
>> + return -EINVAL;
>> +
>> + kvm = zdev->kzdev->kvm;
>> + ioat = &zdev->kzdev->ioat;
>> + mutex_lock(&ioat->lock);
>> + idx = srcu_read_lock(&kvm->srcu);
>> + for (i = 0; i < ZPCI_TABLE_PAGES; i++) {
>> + page = gfn_to_page(kvm, gpa_to_gfn(gpa));
In relation to your question below about where things are being pinned...
Here the call to gfn_to_page does the pin (this call eventually drives
hva_to_pfn for pinning)
>> + if (is_error_page(page)) {
>> + srcu_read_unlock(&kvm->srcu, idx);
>> + rc = -EIO;
>> + goto out;
>> + }
>> + iaddr = page_to_virt(page) + (gpa & ~PAGE_MASK);
>> + ioat->head[i] = (unsigned long *)iaddr;
^^ here we store what was pinned above in ioat->head[] and can use it
later for unpinning.
But looking again now I think for the is_error_page() case above here I
should also be going to unpin: to cleanup in case we were somewhere in
the middle of the loop and so have some pages pinned already.
>> + gpa += PAGE_SIZE;
>> + }
>> + srcu_read_unlock(&kvm->srcu, idx);
>> +
>> + zdev->kzdev->ioat.seg = kcalloc(ZPCI_TABLE_ENTRIES_PAGES,
>> + sizeof(unsigned long *), GFP_KERNEL);
>> + if (!zdev->kzdev->ioat.seg)
>> + goto unpin;
>> + zdev->kzdev->ioat.pt = kcalloc(ZPCI_TABLE_ENTRIES,
>> + sizeof(unsigned long **), GFP_KERNEL);
>> + if (!zdev->kzdev->ioat.pt)
>> + goto free_seg;
>> +
>> +out:
>> + mutex_unlock(&ioat->lock);
>> + return rc;
>> +
>> +free_seg:
>> + kfree(zdev->kzdev->ioat.seg);
>> +unpin:
>> + for (i = 0; i < ZPCI_TABLE_PAGES; i++) {
>> + kvm_release_pfn_dirty((u64)ioat->head[i] >> PAGE_SHIFT);
>
> I did not find when the pages are pinned.
See above.
>
>> + ioat->head[i] = 0;
>> + }
>> + mutex_unlock(&ioat->lock);
>> + return -ENOMEM;
>> +}
>> +EXPORT_SYMBOL_GPL(kvm_s390_pci_ioat_enable);
>> +
>
> ...snip...
>>
>
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