diff options
| author | Tom Lendacky <thomas.lendacky@amd.com> | 2022-09-30 10:14:29 -0500 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2023-04-28 12:50:34 +0200 |
| commit | 8168fed9f84e3128f7628969ae78af49433d5ce7 (patch) | |
| tree | d2d39bd833617b78baec47aee66eff99cb45d786 | |
| parent | 326e3015c4c6f3197157ea0bb00826ae740e2fad (diff) | |
| download | qemu-8168fed9f84e3128f7628969ae78af49433d5ce7.zip qemu-8168fed9f84e3128f7628969ae78af49433d5ce7.tar.gz qemu-8168fed9f84e3128f7628969ae78af49433d5ce7.tar.bz2 | |
i386/sev: Update checks and information related to reduced-phys-bits
The value of the reduced-phys-bits parameter is propogated to the CPUID
information exposed to the guest. Update the current validation check to
account for the size of the CPUID field (6-bits), ensuring the value is
in the range of 1 to 63.
Maintain backward compatibility, to an extent, by allowing a value greater
than 1 (so that the previously documented value of 5 still works), but not
allowing anything over 63.
Fixes: d8575c6c02 ("sev/i386: add command to initialize the memory encryption context")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <cca5341a95ac73f904e6300f10b04f9c62e4e8ff.1664550870.git.thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | target/i386/sev.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/target/i386/sev.c b/target/i386/sev.c index 859e06f..fe2144c 100644 --- a/target/i386/sev.c +++ b/target/i386/sev.c @@ -932,15 +932,26 @@ int sev_kvm_init(ConfidentialGuestSupport *cgs, Error **errp) host_cpuid(0x8000001F, 0, NULL, &ebx, NULL, NULL); host_cbitpos = ebx & 0x3f; + /* + * The cbitpos value will be placed in bit positions 5:0 of the EBX + * register of CPUID 0x8000001F. No need to verify the range as the + * comparison against the host value accomplishes that. + */ if (host_cbitpos != sev->cbitpos) { error_setg(errp, "%s: cbitpos check failed, host '%d' requested '%d'", __func__, host_cbitpos, sev->cbitpos); goto err; } - if (sev->reduced_phys_bits < 1) { - error_setg(errp, "%s: reduced_phys_bits check failed, it should be >=1," - " requested '%d'", __func__, sev->reduced_phys_bits); + /* + * The reduced-phys-bits value will be placed in bit positions 11:6 of + * the EBX register of CPUID 0x8000001F, so verify the supplied value + * is in the range of 1 to 63. + */ + if (sev->reduced_phys_bits < 1 || sev->reduced_phys_bits > 63) { + error_setg(errp, "%s: reduced_phys_bits check failed," + " it should be in the range of 1 to 63, requested '%d'", + __func__, sev->reduced_phys_bits); goto err; } |