| Message ID | 1668624097-14884-7-git-send-email-mikelley@microsoft.com |
|---|---|
| State | New |
| Headers | show |
| Series | Add PCI pass-thru support to Hyper-V Confidential VMs | expand |
On 11/16/22 12:41, Michael Kelley wrote: > Full Hyper-V initialization, including support for hypercalls, is done > as an apic_post_init callback via late_time_init(). mem_encrypt_init() > needs to make hypercalls when it marks swiotlb memory as decrypted. > But mem_encrypt_init() is currently called a few lines before > late_time_init(), so the hypercalls don't work. > > Fix this by moving mem_encrypt_init() after late_time_init() and > related clock initializations. The intervening initializations don't > do any I/O that requires the swiotlb, so moving mem_encrypt_init() > slightly later has no impact. > > Signed-off-by: Michael Kelley <mikelley@microsoft.com> Some quick testing with mem_encrypt_init() in the new location hasn't shown any problems under SME/SEV. Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> > --- > init/main.c | 19 +++++++++++-------- > 1 file changed, 11 insertions(+), 8 deletions(-) > > diff --git a/init/main.c b/init/main.c > index e1c3911..5a7c466 100644 > --- a/init/main.c > +++ b/init/main.c > @@ -1088,14 +1088,6 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void) > */ > locking_selftest(); > > - /* > - * This needs to be called before any devices perform DMA > - * operations that might use the SWIOTLB bounce buffers. It will > - * mark the bounce buffers as decrypted so that their usage will > - * not cause "plain-text" data to be decrypted when accessed. > - */ > - mem_encrypt_init(); > - > #ifdef CONFIG_BLK_DEV_INITRD > if (initrd_start && !initrd_below_start_ok && > page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) { > @@ -1112,6 +1104,17 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void) > late_time_init(); > sched_clock_init(); > calibrate_delay(); > + > + /* > + * This needs to be called before any devices perform DMA > + * operations that might use the SWIOTLB bounce buffers. It will > + * mark the bounce buffers as decrypted so that their usage will > + * not cause "plain-text" data to be decrypted when accessed. It > + * must be called after late_time_init() so that Hyper-V x86/x64 > + * hypercalls work when the SWIOTLB bounce buffers are decrypted. > + */ > + mem_encrypt_init(); > + > pid_idr_init(); > anon_vma_init(); > #ifdef CONFIG_X86
On Wed, Nov 16, 2022 at 10:41:29AM -0800, Michael Kelley wrote: > Fix this by moving mem_encrypt_init() after late_time_init() and > related clock initializations. The intervening initializations don't > do any I/O that requires the swiotlb, so moving mem_encrypt_init() > slightly later has no impact. I hope you're right. Our boot ordering is fragile as hell. But mem_encrypt_init() doesn't do a whole lot of important setup - that has happened a lot earlier already - so I'm not too worried. But we'll see what breaks in wider testing.
diff --git a/init/main.c b/init/main.c index e1c3911..5a7c466 100644 --- a/init/main.c +++ b/init/main.c @@ -1088,14 +1088,6 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void) */ locking_selftest(); - /* - * This needs to be called before any devices perform DMA - * operations that might use the SWIOTLB bounce buffers. It will - * mark the bounce buffers as decrypted so that their usage will - * not cause "plain-text" data to be decrypted when accessed. - */ - mem_encrypt_init(); - #ifdef CONFIG_BLK_DEV_INITRD if (initrd_start && !initrd_below_start_ok && page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) { @@ -1112,6 +1104,17 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void) late_time_init(); sched_clock_init(); calibrate_delay(); + + /* + * This needs to be called before any devices perform DMA + * operations that might use the SWIOTLB bounce buffers. It will + * mark the bounce buffers as decrypted so that their usage will + * not cause "plain-text" data to be decrypted when accessed. It + * must be called after late_time_init() so that Hyper-V x86/x64 + * hypercalls work when the SWIOTLB bounce buffers are decrypted. + */ + mem_encrypt_init(); + pid_idr_init(); anon_vma_init(); #ifdef CONFIG_X86
Full Hyper-V initialization, including support for hypercalls, is done as an apic_post_init callback via late_time_init(). mem_encrypt_init() needs to make hypercalls when it marks swiotlb memory as decrypted. But mem_encrypt_init() is currently called a few lines before late_time_init(), so the hypercalls don't work. Fix this by moving mem_encrypt_init() after late_time_init() and related clock initializations. The intervening initializations don't do any I/O that requires the swiotlb, so moving mem_encrypt_init() slightly later has no impact. Signed-off-by: Michael Kelley <mikelley@microsoft.com> --- init/main.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-)