On Mon, Jan 09, 2023 at 04:05:31AM +0000, Joan Bruguera wrote:
This fixes wakeup for me on both QEMU and real HW
(just a proof of concept, don't merge)
diff --git a/arch/x86/kernel/callthunks.c b/arch/x86/kernel/callthunks.c
index ffea98f9064b..8704bcc0ce32 100644
--- a/arch/x86/kernel/callthunks.c
+++ b/arch/x86/kernel/callthunks.c
@@ -7,6 +7,7 @@
#include <linux/memory.h>
#include <linux/moduleloader.h>
#include <linux/static_call.h>
+#include <linux/suspend.h>
#include <asm/alternative.h>
#include <asm/asm-offsets.h>
@@ -150,6 +151,10 @@ static bool skip_addr(void *dest)
if (dest >= (void *)hypercall_page &&
dest < (void*)hypercall_page + PAGE_SIZE)
return true;
+#endif
+#ifdef CONFIG_PM_SLEEP
+ if (dest == restore_processor_state)
+ return true;
#endif
return false;
}
diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c
index 236447ee9beb..e667894936f7 100644
--- a/arch/x86/power/cpu.c
+++ b/arch/x86/power/cpu.c
@@ -281,6 +281,9 @@ static void notrace __restore_processor_state(struct saved_context *ctxt)
/* Needed by apm.c */
void notrace restore_processor_state(void)
{
+ /* Restore GS before calling anything to avoid crash on call depth accounting */
+ native_wrmsrl(MSR_GS_BASE, saved_context.kernelmode_gs_base);
+
__restore_processor_state(&saved_context);
}
Yeah, I can see why, but I'm not really comfortable with this. TBH, I
don't see how the whole resume code is correct to begin with. At the
very least it needs a heavy dose of noinstr.
Rafael, what cr3 is active when we call restore_processor_state()?
Specifically, the problem is that I don't feel comfortable doing any
sort of weird code until all the CR and segment registers have been
restored, however, write_cr*() are paravirt functions that result in
CALL, which then gives us a bit of a checken and egg problem.
I'm also wondering how well retbleed=stuff works on Xen, if at all. If
we can ignore Xen, things are a little earier perhaps.
Attachment:
OpenPGP_0xB0DE9DD628BF132F.asc
Description: OpenPGP public key
Attachment:
OpenPGP_signature
Description: OpenPGP digital signature