linux-kernel - [RFC 04/16] KVM: selftests: set CPUID before setting sregs in vcpu creation

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Message-Id: <20211006203617.13045-1-michael.roth@amd.com>
Date:   Wed,  6 Oct 2021 15:36:17 -0500
From:   Michael Roth <michael.roth@....com>
To:     linux-kselftest@...r.kernel.org
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org,
        Nathan Tempelman <natet@...gle.com>,
        Marc Orr <marcorr@...gle.com>,
        Steve Rutherford <srutherford@...gle.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Mingwei Zhang <mizhang@...gle.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Varad Gautam <varad.gautam@...e.com>,
        Shuah Khan <shuah@...nel.org>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Ricardo Koller <ricarkol@...gle.com>,
        Jim Mattson <jmattson@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>
Subject: [RFC 04/16] KVM: selftests: set CPUID before setting sregs in vcpu creation

Recent kernels have checks to ensure the GPA values in special-purpose
registers like CR3 are within the maximum physical address range and
don't overlap with anything in the upper/reserved range. In the case of
SEV kselftest guests booting directly into 64-bit mode, CR3 needs to be
initialized to the GPA of the page table root, with the encryption bit
set. The kernel accounts for this encryption bit by removing it from
reserved bit range when the guest advertises the bit position via
KVM_SET_CPUID*, but kselftests currently call KVM_SET_SREGS as part of
vm_vcpu_add_default(), *prior* to vCPU creation, so there's no
opportunity to call KVM_SET_CPUID* in advance. As a result,
KVM_SET_SREGS will return an error in these cases.

Address this by moving vcpu_set_cpuid() (which calls KVM_SET_CPUID*)
ahead of vcpu_setup() (which calls KVM_SET_SREGS).

While there, address a typo in the assertion that triggers when
KVM_SET_SREGS fails.

Suggested-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Michael Roth <michael.roth@....com>
---
 tools/testing/selftests/kvm/lib/kvm_util.c         | 2 +-
 tools/testing/selftests/kvm/lib/x86_64/processor.c | 4 +---
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index ef88fdc7e46b..646cffd86d09 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -1906,7 +1906,7 @@ void vcpu_sregs_get(struct kvm_vm *vm, uint32_t vcpuid, struct kvm_sregs *sregs)
 void vcpu_sregs_set(struct kvm_vm *vm, uint32_t vcpuid, struct kvm_sregs *sregs)
 {
 	int ret = _vcpu_sregs_set(vm, vcpuid, sregs);
-	TEST_ASSERT(ret == 0, "KVM_RUN IOCTL failed, "
+	TEST_ASSERT(ret == 0, "KVM_SET_SREGS IOCTL failed, "
 		"rc: %i errno: %i", ret, errno);
 }
 
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 0bbd88fe1127..1ab4c20f5d12 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -660,6 +660,7 @@ void vm_vcpu_add_default(struct kvm_vm *vm, uint32_t vcpuid, void *guest_code)
 
 	/* Create VCPU */
 	vm_vcpu_add(vm, vcpuid);
+	vcpu_set_cpuid(vm, vcpuid, kvm_get_supported_cpuid());
 	vcpu_setup(vm, vcpuid);
 
 	/* Setup guest general purpose registers */
@@ -672,9 +673,6 @@ void vm_vcpu_add_default(struct kvm_vm *vm, uint32_t vcpuid, void *guest_code)
 	/* Setup the MP state */
 	mp_state.mp_state = 0;
 	vcpu_set_mp_state(vm, vcpuid, &mp_state);
-
-	/* Setup supported CPUIDs */
-	vcpu_set_cpuid(vm, vcpuid, kvm_get_supported_cpuid());
 }
 
 /*
-- 
2.25.1