From 9dbe0c93f00d3aef9ac386c390595d370cfad677 Mon Sep 17 00:00:00 2001 From: Dov Murik Date: Thu, 11 Nov 2021 10:00:44 +0000 Subject: [PATCH] target/i386/sev: Add kernel hashes only if sev-guest.kernel-hashes=on MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit cff03145ed3c ("sev/i386: Introduce sev_add_kernel_loader_hashes for measured linux boot", 2021-09-30) introduced measured direct boot with -kernel, using an OVMF-designated hashes table which QEMU fills. However, if OVMF doesn't designate such an area, QEMU would completely abort the VM launch. This breaks launching with -kernel using older OVMF images which don't publish the SEV_HASH_TABLE_RV_GUID. Fix that so QEMU will only look for the hashes table if the sev-guest kernel-hashes option is set to on. Otherwise, QEMU won't look for the designated area in OVMF and won't fill that area. To enable addition of kernel hashes, launch the guest with: -object sev-guest,...,kernel-hashes=on Signed-off-by: Dov Murik Reported-by: Tom Lendacky Acked-by: Brijesh Singh Signed-off-by: Daniel P. Berrangé --- target/i386/sev.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/target/i386/sev.c b/target/i386/sev.c index cad32812f5..e3abbeef68 100644 --- a/target/i386/sev.c +++ b/target/i386/sev.c @@ -1223,6 +1223,14 @@ bool sev_add_kernel_loader_hashes(SevKernelLoaderContext *ctx, Error **errp) size_t hash_len = HASH_SIZE; int aligned_len; + /* + * Only add the kernel hashes if the sev-guest configuration explicitly + * stated kernel-hashes=on. + */ + if (!sev_guest->kernel_hashes) { + return false; + } + if (!pc_system_ovmf_table_find(SEV_HASH_TABLE_RV_GUID, &data, NULL)) { error_setg(errp, "SEV: kernel specified but OVMF has no hash table guid"); return false;