[PATCH qemu-server 1/3] drive: update TPM size as max of current and minimum size

[Thomas Ellmenreich <t.ellmenreich@proxmox.com>]

The size of a created TPM drive is always based on a constant of 4 MiB, but
if the backing storage has a larger granularity than this, it is
possible to create larger TPM drives. Currently there is no way to deal
with TPM drives, larger then the constant (4MiB), this update to the
helpers introduces this.

Adjust the 'update_tpmstate_size' subroutine so that sets the configured
TPM state size as the max of the actual disk size and a constant
minimum of 4MiB.

Introduce a new 'get_tpmstate_size' subroutine that gets the actual
sizes and performes the max comparison, returing the ideal size.

Suggested-by: Fiona Ebner <f.ebner@proxmox.com>
Signed-off-by: Thomas Ellmenreich <t.ellmenreich@proxmox.com>
---
 src/PVE/QemuMigrate.pm      |  9 ++++----
 src/PVE/QemuServer.pm       |  8 -------
 src/PVE/QemuServer/Drive.pm | 44 +++++++++++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+), 12 deletions(-)

diff --git a/src/PVE/QemuMigrate.pm b/src/PVE/QemuMigrate.pm
index 96035a75..2c9960db 100644
--- a/src/PVE/QemuMigrate.pm
+++ b/src/PVE/QemuMigrate.pm
@@ -30,7 +30,7 @@ use PVE::QemuMigrate::Helpers;
 use PVE::QemuServer::Agent;
 use PVE::QemuServer::BlockJob;
 use PVE::QemuServer::CPUConfig;
-use PVE::QemuServer::Drive qw(checked_volume_format);
+use PVE::QemuServer::Drive qw(checked_volume_format update_tpmstate_size);
 use PVE::QemuServer::Helpers qw(min_version);
 use PVE::QemuServer::Machine;
 use PVE::QemuServer::Monitor qw(mon_cmd vm_qmp_peer);
@@ -685,10 +685,11 @@ sub config_update_local_disksizes {
         PVE::QemuServer::update_efidisk_size($conf);
     }
 
-    # TPM state might have an irregular filesize, to avoid problems on transfer
-    # we always assume the static size of 4M to allocate on the target
+    # TPM state might have an irregular file size, or have increased
+    # significantly due to differences in granularity. To avoid problems on
+    # transfer, update the TPM disk size.
     if (defined($conf->{tpmstate0})) {
-        PVE::QemuServer::update_tpmstate_size($conf);
+        update_tpmstate_size($conf, $self->{storecfg});
     }
 }
 
diff --git a/src/PVE/QemuServer.pm b/src/PVE/QemuServer.pm
index 1efeeb66..954acd05 100644
--- a/src/PVE/QemuServer.pm
+++ b/src/PVE/QemuServer.pm
@@ -7984,14 +7984,6 @@ sub update_efidisk_size {
     return;
 }
 
-sub update_tpmstate_size {
-    my ($conf) = @_;
-
-    my $disk = PVE::QemuServer::parse_drive('tpmstate0', $conf->{tpmstate0});
-    $disk->{size} = PVE::QemuServer::Drive::TPMSTATE_DISK_SIZE;
-    $conf->{tpmstate0} = print_drive($disk);
-}
-
 sub vm_iothreads_list {
     my ($vmid) = @_;
 
diff --git a/src/PVE/QemuServer/Drive.pm b/src/PVE/QemuServer/Drive.pm
index 0b573717..8cda01ef 100644
--- a/src/PVE/QemuServer/Drive.pm
+++ b/src/PVE/QemuServer/Drive.pm
@@ -27,6 +27,8 @@ our @EXPORT_OK = qw(
     parse_drive
     print_drive
     storage_allows_io_uring_default
+    update_tpmstate_size
+    get_tpmstate_size
 );
 
 my $DROPPED_PROPERTIES = ['cyls', 'heads', 'secs', 'trans'];
@@ -1240,4 +1242,46 @@ sub drive_qmp_peer {
     return drive_uses_qsd_fuse($storecfg, $drive) ? qsd_qmp_peer($vmid) : vm_qmp_peer($vmid);
 }
 
+# Takes a VM config and the storage configuration. Parses the configuration,
+# checks the drive size and updates it to the maximum between the actual size
+# and the static TPMSTATE_DISK_SIZE which is 4MiB.
+sub update_tpmstate_size {
+    my ($conf, $storecfg) = @_;
+
+    die "a configuration has to be supplied in which to update the tpm state size"
+        if !defined($conf);
+
+    die "the storage config has to be supplied to determine tpm state size"
+        if !defined($storecfg);
+
+    return if !defined($conf->{tpmstate0});
+
+    my $disk = parse_drive('tpmstate0', $conf->{tpmstate0});
+
+    $disk->{size} = get_tpmstate_size($disk->{file}, $storecfg);
+    $conf->{tpmstate0} = print_drive($disk);
+}
+
+# Takes in a volume id and the storage configuration. Will then try to find
+# the actual storage size of the TPM drive. The final value has a minimum
+# determined by the TPMSTATE_DISK_SIZE static, which is 4MiB.
+sub get_tpmstate_size {
+    my ($volid, $storecfg) = @_;
+
+    die "a volume id has to be supplied to determine tpm state size"
+        if !defined($volid);
+
+    die "the storage config has to be supplied to determine tpm state size"
+        if !defined($storecfg);
+
+    my $size = eval { PVE::Storage::volume_size_info($storecfg, $volid, 10) };
+    warn "failed to get size of the tpm drive $volid: $@" if $@;
+
+    if (!$size || $size < TPMSTATE_DISK_SIZE) {
+        $size = TPMSTATE_DISK_SIZE;
+    }
+
+    return $size;
+}
+
 1;
-- 
2.47.3