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@xxxxxxxxx> --- x86/Makefile.common | 1 + lib/x86/hyperv.h | 1 + x86/hyperv_overlay.c | 96 ++++++++++++++++++++++++++++++++++++++++++++ x86/unittests.cfg | 5 +++ 4 files changed, 103 insertions(+) create mode 100644 x86/hyperv_overlay.c diff --git a/x86/Makefile.common b/x86/Makefile.common index 802f8c1..cb41992 100644 --- a/x86/Makefile.common +++ b/x86/Makefile.common @@ -61,6 +61,7 @@ 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) diff --git a/lib/x86/hyperv.h b/lib/x86/hyperv.h index 889f5a6..e207c69 100644 --- a/lib/x86/hyperv.h +++ b/lib/x86/hyperv.h @@ -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) diff --git a/x86/hyperv_overlay.c b/x86/hyperv_overlay.c new file mode 100644 index 0000000..4472f64 --- /dev/null +++ b/x86/hyperv_overlay.c @@ -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(); +} diff --git a/x86/unittests.cfg b/x86/unittests.cfg index d5efab0..03f7d57 100644 --- a/x86/unittests.cfg +++ b/x86/unittests.cfg @@ -377,6 +377,11 @@ 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 -- 2.17.1 Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B Sitz: Berlin Ust-ID: DE 289 237 879
