@@ -2168,17 +2168,24 @@ void __init sev_hardware_setup(void)
bool sev_es_supported = false;
bool sev_supported = false;
- if (!sev_enabled || !npt_enabled)
+ if (!sev_enabled)
goto out;
+ if (!npt_enabled) {
+ pr_info("Failed to enable AMD SEV as it requires Nested Paging to be enabled\n");
+ goto out;
+ }
+
/*
* SEV must obviously be supported in hardware. Sanity check that the
* CPU supports decode assists, which is mandatory for SEV guests to
* support instruction emulation.
*/
if (!boot_cpu_has(X86_FEATURE_SEV) ||
- WARN_ON_ONCE(!boot_cpu_has(X86_FEATURE_DECODEASSISTS)))
+ WARN_ON_ONCE(!boot_cpu_has(X86_FEATURE_DECODEASSISTS))) {
+ pr_info("Failed to enable AMD SEV as it requires decodeassists and sev CPU features\n");
goto out;
+ }
/* Retrieve SEV CPUID information */
cpuid(0x8000001f, &eax, &ebx, &ecx, &edx);
@@ -2188,8 +2195,10 @@ void __init sev_hardware_setup(void)
/* Maximum number of encrypted guests supported simultaneously */
max_sev_asid = ecx;
- if (!max_sev_asid)
+ if (!max_sev_asid) {
+ pr_info("Failed to enable SEV as the maximum SEV ASID value is 0.\n");
goto out;
+ }
/* Minimum ASID value that should be used for SEV guest */
min_sev_asid = edx;
@@ -2234,16 +2243,22 @@ void __init sev_hardware_setup(void)
* instead relies on #NPF(RSVD) being reflected into the guest as #VC
* (the guest can then do a #VMGEXIT to request MMIO emulation).
*/
- if (!enable_mmio_caching)
+ if (!enable_mmio_caching) {
+ pr_info("Failed to enable SEV-ES as it requires MMIO caching to be enabled\n");
goto out;
+ }
/* Does the CPU support SEV-ES? */
- if (!boot_cpu_has(X86_FEATURE_SEV_ES))
+ if (!boot_cpu_has(X86_FEATURE_SEV_ES)) {
+ pr_info("Failed to enable SEV-ES as it requires sev_es CPU feature\n");
goto out;
+ }
/* Has the system been allocated ASIDs for SEV-ES? */
- if (min_sev_asid == 1)
+ if (min_sev_asid == 1) {
+ pr_info("Failed to enable SEV-ES as the minimum SEV ASID value is 1.\n");
goto out;
+ }
sev_es_asid_count = min_sev_asid - 1;
if (misc_cg_set_capacity(MISC_CG_RES_SEV_ES, sev_es_asid_count))
Let's add a few pr_info's to sev_hardware_setup to make SEV/SEV-ES enabling a little bit handier for users. Right now it's too hard to guess why SEV/SEV-ES are failing to enable. There are a few reasons. SEV: - NPT is disabled (module parameter) - CPU lacks some features (sev, decodeassists) - Maximum SEV ASID is 0 SEV-ES: - mmio_caching is disabled (module parameter) - CPU lacks sev_es feature - Minimum SEV ASID value is 1 (can be adjusted in BIOS/UEFI) Cc: Sean Christopherson <seanjc@google.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Stéphane Graber <stgraber@ubuntu.com> Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> --- arch/x86/kvm/svm/sev.c | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-)