diff options
| author | Paolo Bonzini <[email protected]> | 2024-09-12 11:07:15 -0400 |
|---|---|---|
| committer | Paolo Bonzini <[email protected]> | 2024-09-17 11:38:19 -0400 |
| commit | 55f50b2f86929ae042cd2eee8b2e8ffe00b5a885 (patch) | |
| tree | 233e06994cdde602da0703ba6ede84a503884ff7 /tools/testing/selftests/kvm/memslot_perf_test.c | |
| parent | 356dab4efd1a661c7882010c34594fe9cb0048f3 (diff) | |
| parent | 61de4c34b51c5b9c7ef8229eb246346254638446 (diff) | |
Merge branch 'kvm-memslot-zap-quirk' into HEAD
Today whenever a memslot is moved or deleted, KVM invalidates the entire
page tables and generates fresh ones based on the new memslot layout.
This behavior traditionally was kept because of a bug which was never
fully investigated and caused VM instability with assigned GeForce
GPUs. It generally does not have a huge overhead, because the old
MMU is able to reuse cached page tables and the new one is more
scalabale and can resolve EPT violations/nested page faults in parallel,
but it has worse performance if the guest frequently deletes and
adds small memslots, and it's entirely not viable for TDX. This is
because TDX requires re-accepting of private pages after page dropping.
For non-TDX VMs, this series therefore introduces the
KVM_X86_QUIRK_SLOT_ZAP_ALL quirk, enabling users to control the behavior
of memslot zapping when a memslot is moved/deleted. The quirk is turned
on by default, leading to the zapping of all SPTEs when a memslot is
moved/deleted; users however have the option to turn off the quirk,
which limits the zapping only to those SPTEs hat lie within the range
of memslot being moved/deleted.
Signed-off-by: Paolo Bonzini <[email protected]>
Diffstat (limited to 'tools/testing/selftests/kvm/memslot_perf_test.c')
| -rw-r--r-- | tools/testing/selftests/kvm/memslot_perf_test.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/tools/testing/selftests/kvm/memslot_perf_test.c b/tools/testing/selftests/kvm/memslot_perf_test.c index 579a64f97333..893366982f77 100644 --- a/tools/testing/selftests/kvm/memslot_perf_test.c +++ b/tools/testing/selftests/kvm/memslot_perf_test.c @@ -113,6 +113,7 @@ static_assert(ATOMIC_BOOL_LOCK_FREE == 2, "atomic bool is not lockless"); static sem_t vcpu_ready; static bool map_unmap_verify; +static bool disable_slot_zap_quirk; static bool verbose; #define pr_info_v(...) \ @@ -578,6 +579,9 @@ static bool test_memslot_move_prepare(struct vm_data *data, uint32_t guest_page_size = data->vm->page_size; uint64_t movesrcgpa, movetestgpa; + if (disable_slot_zap_quirk) + vm_enable_cap(data->vm, KVM_CAP_DISABLE_QUIRKS2, KVM_X86_QUIRK_SLOT_ZAP_ALL); + movesrcgpa = vm_slot2gpa(data, data->nslots - 1); if (isactive) { @@ -896,6 +900,7 @@ static void help(char *name, struct test_args *targs) pr_info(" -h: print this help screen.\n"); pr_info(" -v: enable verbose mode (not for benchmarking).\n"); pr_info(" -d: enable extra debug checks.\n"); + pr_info(" -q: Disable memslot zap quirk during memslot move.\n"); pr_info(" -s: specify memslot count cap (-1 means no cap; currently: %i)\n", targs->nslots); pr_info(" -f: specify the first test to run (currently: %i; max %zu)\n", @@ -954,7 +959,7 @@ static bool parse_args(int argc, char *argv[], uint32_t max_mem_slots; int opt; - while ((opt = getopt(argc, argv, "hvds:f:e:l:r:")) != -1) { + while ((opt = getopt(argc, argv, "hvdqs:f:e:l:r:")) != -1) { switch (opt) { case 'h': default: @@ -966,6 +971,11 @@ static bool parse_args(int argc, char *argv[], case 'd': map_unmap_verify = true; break; + case 'q': + disable_slot_zap_quirk = true; + TEST_REQUIRE(kvm_check_cap(KVM_CAP_DISABLE_QUIRKS2) & + KVM_X86_QUIRK_SLOT_ZAP_ALL); + break; case 's': targs->nslots = atoi_paranoid(optarg); if (targs->nslots <= 1 && targs->nslots != -1) { |