[PATCH v2 139/144] KVM: selftests: Trust that MAXPHYADDR > memslot0 in vmx_apic_access_test

Sean Christopherson
2022-06-03T01:01:23Z

Use vm->max_gfn to compute the highest gpa in vmx_apic_access_test, and
blindly trust that the highest gfn/gpa will be well above the memory
carved out for memslot0. The existing check is beyond paranoid; KVM
doesn't support CPUs with host.MAXPHYADDR < 32, and the selftests are all
kinds of hosed if memslot0 overlaps the local xAPIC, which resides above
"lower" (below 4gb) DRAM.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
.../testing/selftests/kvm/x86_64/vmx_apic_access_test.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c b/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c
index ef7514376b1e..ccb05ef7234e 100644
--- a/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c
+++ b/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c
@@ -72,8 +72,6 @@ static void l1_guest_code(struct vmx_pages *vmx_pages, unsigned long high_gpa)
int main(int argc, char *argv[])
{
unsigned long apic_access_addr = ~0ul;
- unsigned int paddr_width;
- unsigned int vaddr_width;
vm_vaddr_t vmx_pages_gva;
unsigned long high_gpa;
struct vmx_pages *vmx;
@@ -86,12 +84,7 @@ int main(int argc, char *argv[])

vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code);

- kvm_get_cpu_address_width(&paddr_width, &vaddr_width);
- high_gpa = (1ul << paddr_width) - getpagesize();
- if ((unsigned long)DEFAULT_GUEST_PHY_PAGES * getpagesize() > high_gpa) {
- print_skip("No unbacked physical page available");
- exit(KSFT_SKIP);
- }
+ high_gpa = (vm->max_gfn - 1) << vm->page_shift;

vmx = vcpu_alloc_vmx(vm, &vmx_pages_gva);
prepare_virtualize_apic_accesses(vmx, vm);
--
2.36.1.255.ge46751e96f-goog