2023-04-27 20:22:01

by Peter Xu

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Subject: [PATCH 0/2] selftests/kvm: Fixes for demand paging test

Two trivial fixes per subject, please see each patch, thanks.

Peter Xu (2):
selftests/kvm: Setup vcpu_alias only for minor mode test
selftests/kvm: Allow dump per-vcpu info for uffd threads

.../testing/selftests/kvm/demand_paging_test.c | 17 +++++++++--------
.../selftests/kvm/lib/userfaultfd_util.c | 4 ++--
2 files changed, 11 insertions(+), 10 deletions(-)

--
2.39.1


2023-04-27 20:22:50

by Peter Xu

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Subject: [PATCH 1/2] selftests/kvm: Setup vcpu_alias only for minor mode test

This fixes two things:

- Unbreaks MISSING mode test on anonymous memory type

- Prefault alias mem before uffd thread creations, otherwise the uffd
thread timing will be inaccurate when guest mem size is large, because
it'll take prefault time into total time.

Signed-off-by: Peter Xu <[email protected]>
---
.../testing/selftests/kvm/demand_paging_test.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
index 2439c4043fed..9c18686b4f63 100644
--- a/tools/testing/selftests/kvm/demand_paging_test.c
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -128,6 +128,7 @@ static void prefault_mem(void *alias, uint64_t len)

static void run_test(enum vm_guest_mode mode, void *arg)
{
+ struct memstress_vcpu_args *vcpu_args;
struct test_params *p = arg;
struct uffd_desc **uffd_descs = NULL;
struct timespec start;
@@ -145,24 +146,24 @@ static void run_test(enum vm_guest_mode mode, void *arg)
"Failed to allocate buffer for guest data pattern");
memset(guest_data_prototype, 0xAB, demand_paging_size);

+ if (p->uffd_mode == UFFDIO_REGISTER_MODE_MINOR) {
+ for (i = 0; i < nr_vcpus; i++) {
+ vcpu_args = &memstress_args.vcpu_args[i];
+ prefault_mem(addr_gpa2alias(vm, vcpu_args->gpa),
+ vcpu_args->pages * memstress_args.guest_page_size);
+ }
+ }
+
if (p->uffd_mode) {
uffd_descs = malloc(nr_vcpus * sizeof(struct uffd_desc *));
TEST_ASSERT(uffd_descs, "Memory allocation failed");
-
for (i = 0; i < nr_vcpus; i++) {
- struct memstress_vcpu_args *vcpu_args;
void *vcpu_hva;
- void *vcpu_alias;

vcpu_args = &memstress_args.vcpu_args[i];

/* Cache the host addresses of the region */
vcpu_hva = addr_gpa2hva(vm, vcpu_args->gpa);
- vcpu_alias = addr_gpa2alias(vm, vcpu_args->gpa);
-
- prefault_mem(vcpu_alias,
- vcpu_args->pages * memstress_args.guest_page_size);
-
/*
* Set up user fault fd to handle demand paging
* requests.
--
2.39.1

2023-04-27 20:39:58

by James Houghton

[permalink] [raw]
Subject: Re: [PATCH 1/2] selftests/kvm: Setup vcpu_alias only for minor mode test

On Thu, Apr 27, 2023 at 1:11 PM Peter Xu <[email protected]> wrote:
>
> This fixes two things:
>
> - Unbreaks MISSING mode test on anonymous memory type
>
> - Prefault alias mem before uffd thread creations, otherwise the uffd
> thread timing will be inaccurate when guest mem size is large, because
> it'll take prefault time into total time.
>
> Signed-off-by: Peter Xu <[email protected]>

Reviewed-by: James Houghton <[email protected]>

FWIW, it looks like this fixes this commit[1]. Not sure if it's worth
a Fixes: tag.

[1]: commit a93871d0ea9f ("KVM: selftests: Add a userfaultfd library")


> ---
> .../testing/selftests/kvm/demand_paging_test.c | 17 +++++++++--------
> 1 file changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
> index 2439c4043fed..9c18686b4f63 100644
> --- a/tools/testing/selftests/kvm/demand_paging_test.c
> +++ b/tools/testing/selftests/kvm/demand_paging_test.c
> @@ -128,6 +128,7 @@ static void prefault_mem(void *alias, uint64_t len)
>
> static void run_test(enum vm_guest_mode mode, void *arg)
> {
> + struct memstress_vcpu_args *vcpu_args;
> struct test_params *p = arg;
> struct uffd_desc **uffd_descs = NULL;
> struct timespec start;
> @@ -145,24 +146,24 @@ static void run_test(enum vm_guest_mode mode, void *arg)
> "Failed to allocate buffer for guest data pattern");
> memset(guest_data_prototype, 0xAB, demand_paging_size);
>
> + if (p->uffd_mode == UFFDIO_REGISTER_MODE_MINOR) {
> + for (i = 0; i < nr_vcpus; i++) {
> + vcpu_args = &memstress_args.vcpu_args[i];
> + prefault_mem(addr_gpa2alias(vm, vcpu_args->gpa),
> + vcpu_args->pages * memstress_args.guest_page_size);
> + }
> + }
> +
> if (p->uffd_mode) {
> uffd_descs = malloc(nr_vcpus * sizeof(struct uffd_desc *));
> TEST_ASSERT(uffd_descs, "Memory allocation failed");
> -
> for (i = 0; i < nr_vcpus; i++) {
> - struct memstress_vcpu_args *vcpu_args;
> void *vcpu_hva;
> - void *vcpu_alias;
>
> vcpu_args = &memstress_args.vcpu_args[i];
>
> /* Cache the host addresses of the region */
> vcpu_hva = addr_gpa2hva(vm, vcpu_args->gpa);
> - vcpu_alias = addr_gpa2alias(vm, vcpu_args->gpa);
> -
> - prefault_mem(vcpu_alias,
> - vcpu_args->pages * memstress_args.guest_page_size);
> -
> /*
> * Set up user fault fd to handle demand paging
> * requests.
> --
> 2.39.1
>

2023-06-02 01:54:43

by Sean Christopherson

[permalink] [raw]
Subject: Re: [PATCH 0/2] selftests/kvm: Fixes for demand paging test

On Thu, 27 Apr 2023 16:11:10 -0400, Peter Xu wrote:
> Two trivial fixes per subject, please see each patch, thanks.
>
> Peter Xu (2):
> selftests/kvm: Setup vcpu_alias only for minor mode test
> selftests/kvm: Allow dump per-vcpu info for uffd threads
>
> .../testing/selftests/kvm/demand_paging_test.c | 17 +++++++++--------
> .../selftests/kvm/lib/userfaultfd_util.c | 4 ++--
> 2 files changed, 11 insertions(+), 10 deletions(-)
>
> [...]

Applied to kvm-x86 selftests, thanks!

[1/2] selftests/kvm: Setup vcpu_alias only for minor mode test
https://github.com/kvm-x86/linux/commit/ba125de35da5
[2/2] selftests/kvm: Allow dump per-vcpu info for uffd threads
https://github.com/kvm-x86/linux/commit/21912a653d7d

--
https://github.com/kvm-x86/linux/tree/next
https://github.com/kvm-x86/linux/tree/fixes