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Subject[PATCH 32/40] KVM: remove the vmap usage
Date
From: Izik Eidus <ieidus@redhat.com>

vmap() on guest pages hides those pages from the Linux mm for an extended
(userspace determined) amount of time. Get rid of it.

Signed-off-by: Izik Eidus <ieidus@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
---
arch/x86/kvm/x86.c | 62 +++++++++-----------------------------------
include/linux/kvm_types.h | 3 +-
2 files changed, 14 insertions(+), 51 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 67f9176..2a4f3a6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2371,40 +2371,19 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
}
EXPORT_SYMBOL_GPL(emulate_instruction);

-static void free_pio_guest_pages(struct kvm_vcpu *vcpu)
-{
- int i;
-
- for (i = 0; i < ARRAY_SIZE(vcpu->arch.pio.guest_pages); ++i)
- if (vcpu->arch.pio.guest_pages[i]) {
- kvm_release_page_dirty(vcpu->arch.pio.guest_pages[i]);
- vcpu->arch.pio.guest_pages[i] = NULL;
- }
-}
-
static int pio_copy_data(struct kvm_vcpu *vcpu)
{
void *p = vcpu->arch.pio_data;
- void *q;
+ gva_t q = vcpu->arch.pio.guest_gva;
unsigned bytes;
- int nr_pages = vcpu->arch.pio.guest_pages[1] ? 2 : 1;
+ int ret;

- q = vmap(vcpu->arch.pio.guest_pages, nr_pages, VM_READ|VM_WRITE,
- PAGE_KERNEL);
- if (!q) {
- free_pio_guest_pages(vcpu);
- return -ENOMEM;
- }
- q += vcpu->arch.pio.guest_page_offset;
bytes = vcpu->arch.pio.size * vcpu->arch.pio.cur_count;
if (vcpu->arch.pio.in)
- memcpy(q, p, bytes);
+ ret = kvm_write_guest_virt(q, p, bytes, vcpu);
else
- memcpy(p, q, bytes);
- q -= vcpu->arch.pio.guest_page_offset;
- vunmap(q);
- free_pio_guest_pages(vcpu);
- return 0;
+ ret = kvm_read_guest_virt(q, p, bytes, vcpu);
+ return ret;
}

int complete_pio(struct kvm_vcpu *vcpu)
@@ -2515,7 +2494,6 @@ int kvm_emulate_pio(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
vcpu->arch.pio.in = in;
vcpu->arch.pio.string = 0;
vcpu->arch.pio.down = 0;
- vcpu->arch.pio.guest_page_offset = 0;
vcpu->arch.pio.rep = 0;

if (vcpu->run->io.direction == KVM_EXIT_IO_IN)
@@ -2543,9 +2521,7 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
gva_t address, int rep, unsigned port)
{
unsigned now, in_page;
- int i, ret = 0;
- int nr_pages = 1;
- struct page *page;
+ int ret = 0;
struct kvm_io_device *pio_dev;

vcpu->run->exit_reason = KVM_EXIT_IO;
@@ -2557,7 +2533,6 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
vcpu->arch.pio.in = in;
vcpu->arch.pio.string = 1;
vcpu->arch.pio.down = down;
- vcpu->arch.pio.guest_page_offset = offset_in_page(address);
vcpu->arch.pio.rep = rep;

if (vcpu->run->io.direction == KVM_EXIT_IO_IN)
@@ -2577,15 +2552,8 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
else
in_page = offset_in_page(address) + size;
now = min(count, (unsigned long)in_page / size);
- if (!now) {
- /*
- * String I/O straddles page boundary. Pin two guest pages
- * so that we satisfy atomicity constraints. Do just one
- * transaction to avoid complexity.
- */
- nr_pages = 2;
+ if (!now)
now = 1;
- }
if (down) {
/*
* String I/O in reverse. Yuck. Kill the guest, fix later.
@@ -2600,15 +2568,7 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
if (vcpu->arch.pio.cur_count == vcpu->arch.pio.count)
kvm_x86_ops->skip_emulated_instruction(vcpu);

- for (i = 0; i < nr_pages; ++i) {
- page = gva_to_page(vcpu, address + i * PAGE_SIZE);
- vcpu->arch.pio.guest_pages[i] = page;
- if (!page) {
- kvm_inject_gp(vcpu, 0);
- free_pio_guest_pages(vcpu);
- return 1;
- }
- }
+ vcpu->arch.pio.guest_gva = address;

pio_dev = vcpu_find_pio_dev(vcpu, port,
vcpu->arch.pio.cur_count,
@@ -2616,7 +2576,11 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
if (!vcpu->arch.pio.in) {
/* string PIO write */
ret = pio_copy_data(vcpu);
- if (ret >= 0 && pio_dev) {
+ if (ret == X86EMUL_PROPAGATE_FAULT) {
+ kvm_inject_gp(vcpu, 0);
+ return 1;
+ }
+ if (ret == 0 && pio_dev) {
pio_string_write(pio_dev, vcpu);
complete_pio(vcpu);
if (vcpu->arch.pio.count == 0)
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index 9b6f395..5f4a18c 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -43,8 +43,7 @@ typedef hfn_t pfn_t;
struct kvm_pio_request {
unsigned long count;
int cur_count;
- struct page *guest_pages[2];
- unsigned guest_page_offset;
+ gva_t guest_gva;
int in;
int port;
int size;
--
1.6.0.6


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