@@ -62,6 +62,7 @@ tests-common = $(TEST_DIR)/vmexit.flat $(TEST_DIR)/tsc.flat \
$(TEST_DIR)/init.flat $(TEST_DIR)/smap.flat \
$(TEST_DIR)/hyperv_synic.flat $(TEST_DIR)/hyperv_stimer.flat \
$(TEST_DIR)/hyperv_connections.flat \
+ $(TEST_DIR)/hyperv_overlay.flat \
$(TEST_DIR)/umip.flat $(TEST_DIR)/tsx-ctrl.flat
test_cases: $(tests-common) $(tests)
@@ -82,6 +83,8 @@ $(TEST_DIR)/hyperv_stimer.elf: $(TEST_DIR)/hyperv.o
$(TEST_DIR)/hyperv_connections.elf: $(TEST_DIR)/hyperv.o
+$(TEST_DIR)/hyperv_overlay.elf: $(TEST_DIR)/hyperv.o
+
arch_clean:
$(RM) $(TEST_DIR)/*.o $(TEST_DIR)/*.flat $(TEST_DIR)/*.elf \
$(TEST_DIR)/.*.d lib/x86/.*.d \
@@ -52,6 +52,7 @@
#define HV_X64_MSR_STIMER3_CONFIG 0x400000B6
#define HV_X64_MSR_STIMER3_COUNT 0x400000B7
+#define HV_OVERLAY_ENABLE (1ULL << 0)
#define HV_SYNIC_CONTROL_ENABLE (1ULL << 0)
#define HV_SYNIC_SIMP_ENABLE (1ULL << 0)
#define HV_SYNIC_SIEFP_ENABLE (1ULL << 0)
new file mode 100644
@@ -0,0 +1,96 @@
+#include "vm.h"
+#include "hyperv.h"
+#include "alloc_page.h"
+
+/**
+ * Test if the underlying GPA contents are preserved when an
+ * overlay is mounted there.
+ */
+static int test_underlay_intact(void *page, u64 msr)
+{
+ int i;
+ u64 gpa = (u64)virt_to_phys(page);
+
+ memset(page, 0xAA, PAGE_SIZE);
+
+ /* Enable overlay */
+ wrmsr(msr, gpa | HV_OVERLAY_ENABLE);
+
+ /* Write to overlay */
+ memset(page, 0x55, PAGE_SIZE);
+
+ /* Disable overlay */
+ wrmsr(msr, 0);
+
+ for (i = 0; i < PAGE_SIZE; i++)
+ if (((u8 *)page)[i] != 0xAA)
+ return -1;
+
+ return 0;
+}
+
+/**
+ * Test if Guest OS ID reset unmounts hypercall overlay and
+ * exposes the underlying page.
+ */
+static int test_guest_os_id_reset(void *page)
+{
+ int i;
+ u64 gpa = (u64)virt_to_phys(page);
+
+ memset(page, 0xAA, PAGE_SIZE);
+
+ /* Enable overlay */
+ wrmsr(HV_X64_MSR_HYPERCALL, gpa | HV_OVERLAY_ENABLE);
+
+ /* Write to overlay */
+ memset(page, 0x55, PAGE_SIZE);
+
+ /* Guest OS ID reset forces overlay unmap */
+ wrmsr(HV_X64_MSR_GUEST_OS_ID, 0);
+
+ for (i = 0; i < PAGE_SIZE; i++)
+ if (((u8 *)page)[i] != 0xAA)
+ return -1;
+
+ return 0;
+}
+
+int main(int ac, char **av)
+{
+ int rc;
+ void *page;
+ u64 guestid = (0x8f00ull << 48);
+
+ setup_vm();
+
+ page = alloc_page();
+ if (!page)
+ report_abort("Failed to allocate page for overlay tests");
+
+ rc = test_underlay_intact(page, HV_X64_MSR_HYPERCALL);
+ report(rc != 0, "Hypercall page before guest OS ID write");
+
+ wrmsr(HV_X64_MSR_GUEST_OS_ID, guestid);
+ rc = test_underlay_intact(page, HV_X64_MSR_HYPERCALL);
+ report(rc == 0, "Hypercall page after guest OS ID write");
+
+ rc = test_guest_os_id_reset(page);
+ report(rc == 0, "Guest OS ID reset removes hcall overlay");
+
+ if (!synic_supported()) {
+ report_skip("Hyper-V SynIC is not supported");
+ goto summary;
+ }
+
+ rc = test_underlay_intact(page, HV_X64_MSR_SIMP);
+ report(rc == 0, "SynIC message page");
+
+ rc = test_underlay_intact(page, HV_X64_MSR_SIEFP);
+ report(rc == 0, "SynIC event page");
+
+ free_page(page);
+
+summary:
+ return report_summary();
+}
@@ -372,6 +372,11 @@ arch = x86_64
groups = hyperv
check = /sys/devices/system/clocksource/clocksource0/current_clocksource=tsc
+[hyperv_overlay]
+file = hyperv_overlay.flat
+extra_params = -cpu kvm64,hv_vpindex,hv_synic
+groups = hyperv
+
[intel_iommu]
file = intel-iommu.flat
arch = x86_64
Patch series [1] starts treating hypercall code page as an overlay page (along with the existing synic event and message pages). Add KVM unit tests to make sure the underlying page contents are intact with various overlay workflows. [1]: https://www.spinics.net/lists/kvm/msg244569.html Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de> --- x86/Makefile.common | 3 ++ x86/hyperv.h | 1 + x86/hyperv_overlay.c | 96 ++++++++++++++++++++++++++++++++++++++++++++ x86/unittests.cfg | 5 +++ 4 files changed, 105 insertions(+) create mode 100644 x86/hyperv_overlay.c