Extend the existing sev_exitlib with helpers for handling pvalidate
instructions and issuing page-state changes via the GHCB MSR protocol.
Subsequent SEV-SNP-related tests will make use of these in guest code.
Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
---
.../kvm/include/x86_64/sev_exitlib.h | 6 ++
.../selftests/kvm/lib/x86_64/sev_exitlib.c | 77 +++++++++++++++++++
2 files changed, 83 insertions(+)
diff --git a/tools/testing/selftests/kvm/include/x86_64/sev_exitlib.h b/tools/testing/selftests/kvm/include/x86_64/sev_exitlib.h
index 4b67b4004dfa..5c7356f9e925 100644
--- a/tools/testing/selftests/kvm/include/x86_64/sev_exitlib.h
+++ b/tools/testing/selftests/kvm/include/x86_64/sev_exitlib.h
@@ -8,7 +8,13 @@
#ifndef SELFTEST_KVM_SEV_EXITLIB_H
#define SELFTEST_KVM_SEV_EXITLIB_H
+#define PVALIDATE_NO_UPDATE 255
+
int sev_es_handle_vc(void *ghcb, u64 ghcb_gpa, struct ex_regs *regs);
void sev_es_terminate(int reason);
+void snp_register_ghcb(u64 ghcb_gpa);
+void snp_psc_set_shared(u64 gpa);
+void snp_psc_set_private(u64 gpa);
+int snp_pvalidate(void *ptr, bool rmp_psize, bool validate);
#endif /* SELFTEST_KVM_SEV_EXITLIB_H */
diff --git a/tools/testing/selftests/kvm/lib/x86_64/sev_exitlib.c b/tools/testing/selftests/kvm/lib/x86_64/sev_exitlib.c
index b3f7b0297e5b..546b402d5015 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/sev_exitlib.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/sev_exitlib.c
@@ -51,6 +51,19 @@
#define GHCB_REG_GPA_RESP(resp) ((resp) & GENMASK_ULL(11, 0))
#define GHCB_REG_GPA_RESP_VAL(resp) ((resp) >> 12)
+/* GHCB MSR protocol for Page State Change */
+#define GHCB_PSC_REQ_PRIVATE 1
+#define GHCB_PSC_REQ_SHARED 2
+#define GHCB_PSC_REQ_PSMASH 3
+#define GHCB_PSC_REQ_UNSMASH 4
+#define GHCB_PSC_REQ_CODE 0x14UL
+#define GHCB_PSC_REQ(gfn, op) \
+ (((unsigned long)((op) & 0xf) << 52) | \
+ ((unsigned long)((gfn) & ~(1ULL << 40)) << 12) | \
+ GHCB_PSC_REQ_CODE)
+#define GHCB_PSC_RESP_CODE 0x15UL
+#define GHCB_PSC_RESP(resp) ((resp) & GENMASK_ULL(11, 0))
+
/* GHCB format/accessors */
struct ghcb {
@@ -247,3 +260,67 @@ int sev_es_handle_vc(void *ghcb, u64 ghcb_gpa, struct ex_regs *regs)
return handle_vc_cpuid(ghcb, ghcb_gpa, regs);
}
+
+void snp_register_ghcb(u64 ghcb_gpa)
+{
+ u64 gfn = ghcb_gpa >> PAGE_SHIFT;
+ u64 resp;
+
+ sev_es_wrmsr_ghcb(GHCB_REG_GPA_REQ(gfn));
+ VMGEXIT();
+
+ resp = sev_es_rdmsr_ghcb();
+ if (GHCB_REG_GPA_RESP(resp) != GHCB_REG_GPA_RESP_CODE ||
+ GHCB_REG_GPA_RESP_VAL(resp) != gfn)
+ sev_es_terminate(GHCB_TERMINATE_REASON_UNSPEC);
+}
+
+static void snp_psc_request(u64 gfn, int op)
+{
+ u64 resp;
+
+ sev_es_wrmsr_ghcb(GHCB_PSC_REQ(gfn, op));
+ VMGEXIT();
+
+ resp = sev_es_rdmsr_ghcb();
+ if (GHCB_PSC_RESP(resp) != GHCB_PSC_RESP_CODE)
+ sev_es_terminate(GHCB_TERMINATE_REASON_UNSPEC);
+}
+
+void snp_psc_set_shared(u64 gpa)
+{
+ snp_psc_request(gpa >> PAGE_SHIFT, GHCB_PSC_REQ_SHARED);
+}
+
+void snp_psc_set_private(u64 gpa)
+{
+ snp_psc_request(gpa >> PAGE_SHIFT, GHCB_PSC_REQ_PRIVATE);
+}
+
+/* From arch/x86/include/asm/asm.h */
+#ifdef __GCC_ASM_FLAG_OUTPUTS__
+# define CC_SET(c) "\n\t/* output condition code " #c "*/\n"
+# define CC_OUT(c) "=@cc" #c
+#else
+# define CC_SET(c) "\n\tset" #c " %[_cc_" #c "]\n"
+# define CC_OUT(c) [_cc_ ## c] "=qm"
+#endif
+
+int snp_pvalidate(void *ptr, bool rmp_psize, bool validate)
+{
+ uint64_t gva = (uint64_t)ptr;
+ bool no_rmpupdate;
+ int rc;
+
+ /* "pvalidate" mnemonic support in binutils 2.36 and newer */
+ asm volatile(".byte 0xF2, 0x0F, 0x01, 0xFF\n\t"
+ CC_SET(c)
+ : CC_OUT(c) (no_rmpupdate), "=a"(rc)
+ : "a"(gva), "c"(rmp_psize), "d"(validate)
+ : "memory", "cc");
+
+ if (no_rmpupdate)
+ return PVALIDATE_NO_UPDATE;
+
+ return rc;
+}
--
2.25.1
