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drm/i915/gvt/kvmgt: read/write GPA via KVM API

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Previously to read/write a GPA, we at first try to pin the GFN it belongs
to, then translate the pinned PFN to a kernel HVA, then read/write it.
This is however not necessary. A GFN should be pinned IFF it would be
accessed by peripheral devices (DMA), not by CPU. This patch changes
the read/write method to KVM API, which will leverage userspace HVA
and copy_{from|to}_usr instead.

Signed-off-by: Jike Song <jike.song@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
This commit is contained in:
Jike Song 2016-12-08 11:00:35 +08:00 committed by Zhenyu Wang
parent c55b1de02d
commit f440c8a572
1 changed files with 16 additions and 21 deletions
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37
drivers/gpu/drm/i915/gvt/kvmgt.c
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@ -31,6 +31,7 @@
#include <linux/init.h>
#include <linux/device.h>
#include <linux/mm.h>
#include <linux/mmu_context.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/rbtree.h>
@ -519,33 +520,27 @@ static unsigned long kvmgt_gfn_to_pfn(unsigned long handle, unsigned long gfn)
return pfn;
}
static void *kvmgt_gpa_to_hva(unsigned long handle, unsigned long gpa)
{
unsigned long pfn;
gfn_t gfn = gpa_to_gfn(gpa);
pfn = kvmgt_gfn_to_pfn(handle, gfn);
if (!pfn)
return NULL;
return (char *)pfn_to_kaddr(pfn) + offset_in_page(gpa);
}
static int kvmgt_rw_gpa(unsigned long handle, unsigned long gpa,
void *buf, unsigned long len, bool write)
{
void *hva = NULL;
struct kvmgt_guest_info *info;
struct kvm *kvm;
int ret;
bool kthread = current->mm == NULL;
hva = kvmgt_gpa_to_hva(handle, gpa);
if (!hva)
return -EFAULT;
info = (struct kvmgt_guest_info *)handle;
kvm = info->kvm;
if (write)
memcpy(hva, buf, len);
else
memcpy(buf, hva, len);
if (kthread)
use_mm(kvm->mm);
return 0;
ret = write ? kvm_write_guest(kvm, gpa, buf, len) :
kvm_read_guest(kvm, gpa, buf, len);
if (kthread)
unuse_mm(kvm->mm);
return ret;
}
static int kvmgt_read_gpa(unsigned long handle, unsigned long gpa,