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122 lines
4.6 KiB
122 lines
4.6 KiB
From adb6c21257cf8b077e8d55c3326549a671a70481 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= <berrange@redhat.com>
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Date: Tue, 30 Jul 2024 10:51:21 +0100
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Subject: [PATCH] Fix detection of TDX confidential VM on Azure platform
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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The original CVM detection logic for TDX assumes that the guest can see
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the standard TDX CPUID leaf. This was true in Azure when this code was
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originally written, however, current Azure now blocks that leaf in the
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paravisor. Instead it is required to use the same Azure specific CPUID
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leaf that is used for SEV-SNP detection, which reports the VM isolation
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type.
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Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
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(cherry picked from commit 9d7be044cad1ae54e344daf8f2ec37da46faf0fd)
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Related: RHEL-50651
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---
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src/basic/confidential-virt.c | 11 ++++++++---
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src/boot/efi/vmm.c | 9 ++++++---
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src/fundamental/confidential-virt-fundamental.h | 1 +
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3 files changed, 15 insertions(+), 6 deletions(-)
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diff --git a/src/basic/confidential-virt.c b/src/basic/confidential-virt.c
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index 64067098e5..0929e0e745 100644
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--- a/src/basic/confidential-virt.c
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+++ b/src/basic/confidential-virt.c
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@@ -77,7 +77,7 @@ static uint64_t msr(uint64_t index) {
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return ret;
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}
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-static bool detect_hyperv_sev(void) {
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+static bool detect_hyperv_cvm(uint32_t isoltype) {
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uint32_t eax, ebx, ecx, edx, feat;
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char sig[13] = {};
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@@ -101,7 +101,7 @@ static bool detect_hyperv_sev(void) {
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ebx = ecx = edx = 0;
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cpuid(&eax, &ebx, &ecx, &edx);
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- if ((ebx & CPUID_HYPERV_ISOLATION_TYPE_MASK) == CPUID_HYPERV_ISOLATION_TYPE_SNP)
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+ if ((ebx & CPUID_HYPERV_ISOLATION_TYPE_MASK) == isoltype)
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return true;
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}
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@@ -134,7 +134,7 @@ static ConfidentialVirtualization detect_sev(void) {
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if (!(eax & EAX_SEV)) {
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log_debug("No sev in CPUID, trying hyperv CPUID");
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- if (detect_hyperv_sev())
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+ if (detect_hyperv_cvm(CPUID_HYPERV_ISOLATION_TYPE_SNP))
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return CONFIDENTIAL_VIRTUALIZATION_SEV_SNP;
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log_debug("No hyperv CPUID");
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@@ -172,6 +172,11 @@ static ConfidentialVirtualization detect_tdx(void) {
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if (memcmp(sig, CPUID_SIG_INTEL_TDX, sizeof(sig)) == 0)
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return CONFIDENTIAL_VIRTUALIZATION_TDX;
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+ log_debug("No tdx in CPUID, trying hyperv CPUID");
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+
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+ if (detect_hyperv_cvm(CPUID_HYPERV_ISOLATION_TYPE_TDX))
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+ return CONFIDENTIAL_VIRTUALIZATION_TDX;
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+
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return CONFIDENTIAL_VIRTUALIZATION_NONE;
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}
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diff --git a/src/boot/efi/vmm.c b/src/boot/efi/vmm.c
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index 214f8f7024..153cafba4e 100644
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--- a/src/boot/efi/vmm.c
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+++ b/src/boot/efi/vmm.c
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@@ -353,7 +353,7 @@ static uint64_t msr(uint32_t index) {
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return val;
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}
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-static bool detect_hyperv_sev(void) {
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+static bool detect_hyperv_cvm(uint32_t isoltype) {
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uint32_t eax, ebx, ecx, edx, feat;
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char sig[13] = {};
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@@ -370,7 +370,7 @@ static bool detect_hyperv_sev(void) {
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if (ebx & CPUID_HYPERV_ISOLATION && !(ebx & CPUID_HYPERV_CPU_MANAGEMENT)) {
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__cpuid(CPUID_HYPERV_ISOLATION_CONFIG, eax, ebx, ecx, edx);
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- if ((ebx & CPUID_HYPERV_ISOLATION_TYPE_MASK) == CPUID_HYPERV_ISOLATION_TYPE_SNP)
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+ if ((ebx & CPUID_HYPERV_ISOLATION_TYPE_MASK) == isoltype)
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return true;
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}
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@@ -395,7 +395,7 @@ static bool detect_sev(void) {
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* specific CPUID checks.
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*/
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if (!(eax & EAX_SEV))
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- return detect_hyperv_sev();
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+ return detect_hyperv_cvm(CPUID_HYPERV_ISOLATION_TYPE_SNP);
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msrval = msr(MSR_AMD64_SEV);
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@@ -419,6 +419,9 @@ static bool detect_tdx(void) {
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if (memcmp(sig, CPUID_SIG_INTEL_TDX, sizeof(sig)) == 0)
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return true;
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+ if (detect_hyperv_cvm(CPUID_HYPERV_ISOLATION_TYPE_TDX))
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+ return true;
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+
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return false;
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}
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#endif /* ! __i386__ && ! __x86_64__ */
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diff --git a/src/fundamental/confidential-virt-fundamental.h b/src/fundamental/confidential-virt-fundamental.h
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index 986923e1c2..618b5800ea 100644
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--- a/src/fundamental/confidential-virt-fundamental.h
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+++ b/src/fundamental/confidential-virt-fundamental.h
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@@ -65,6 +65,7 @@
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#define CPUID_HYPERV_ISOLATION_TYPE_MASK UINT32_C(0xf)
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#define CPUID_HYPERV_ISOLATION_TYPE_SNP 2
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+#define CPUID_HYPERV_ISOLATION_TYPE_TDX 3
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#define EAX_SEV (UINT32_C(1) << 1)
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#define MSR_SEV (UINT64_C(1) << 0)
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