On 8/17/21 12:27 PM, Borislav Petkov wrote:
The majority of kernel code puts __packed after the struct definition,
let's put it there too pls, out of the way.
...
Noted.
+ if (WARN(ret || ghcb->save.sw_exit_info_2,
+ "SEV-SNP: page state change failed ret=%d exit_info_2=%llx\n",
+ ret, ghcb->save.sw_exit_info_2))
+ return 1;
Yikes, you return here and below with interrupts disabled.
All your returns need to be "goto out;" instead where you do
out:
__sev_put_ghcb(&state);
local_irq_restore(flags);
Yap, you very likely need to put the GHCB too.
Sure, let me revisit this code to fix those path.
+ /*
+ * Lets do some sanity check that entry processing is not going
+ * backward. This will happen only if hypervisor is tricking us.
+ */
+ if (WARN((hdr->end_entry > end_entry) || (cur_entry > hdr->cur_entry),
+ "SEV-SNP: page state change processing going backward, end_entry "
+ "(expected %d got %d) cur_entry (expected %d got %d)\n",
+ end_entry, hdr->end_entry, cur_entry, hdr->cur_entry))
+ return 1;
WARNING: quoted string split across lines
#293: FILE: arch/x86/kernel/sev.c:750:
+ "SEV-SNP: page state change processing going backward, end_entry "
+ "(expected %d got %d) cur_entry (expected %d got %d)\n",
If you're wondering what to do, yes, you can really stretch that string
and shorten it too:
Okay.
if (WARN((hdr->end_entry > end_entry) || (cur_entry > hdr->cur_entry),
"SEV-SNP: PSC processing going backwards, end_entry %d (got %d) cur_entry: %d (got %d)\n",
end_entry, hdr->end_entry, cur_entry, hdr->cur_entry))
return 1;
so that it fits on a single line and grepping can find it.
Noted.
+ /* Lets verify that reserved bit is not set in the header*/
+ if (WARN(hdr->reserved, "Reserved bit is set in the PSC header\n"))
psc_entry has a ->reserved field too and since we're iterating over the
entries...
Sure I can add that check.
+
+ desc = kmalloc(sizeof(*desc), GFP_KERNEL_ACCOUNT);
kzalloc() so that you don't have to memset() later in
__set_page_state().
Depending on the size, the __set_page_state() can be call multiple times
so it should clear the desc memory before filling it.
+ if (!desc)
+ panic("failed to allocate memory");
Make that error message more distinctive so that *if* it happens, one
can pinpoint the place in the code where the panic comes from.
Now I am running checkpatch and notice that it complain about the
message too. I can add a BUG() or WARN() to get the stack trace before
the crashing.
+ while (vaddr < vaddr_end) {
+ /*
+ * Calculate the last vaddr that can be fit in one
+ * struct snp_psc_desc.
+ */
+ next_vaddr = min_t(unsigned long, vaddr_end,
+ (VMGEXIT_PSC_MAX_ENTRY * PAGE_SIZE) + vaddr);
+
+ __set_page_state(desc, vaddr, next_vaddr, op);
+
+ vaddr = next_vaddr;
+ }
+
+ kfree(desc);
+}
+
