On 07.02.20 12:39, Christian Borntraeger wrote:
> From: Vasily Gorbik <gor@xxxxxxxxxxxxx>
>
> Add exceptions handlers performing transparent transition of non-secure
> pages to secure (import) upon guest access and secure pages to
> non-secure (export) upon hypervisor access.
>
> Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
> [frankja@xxxxxxxxxxxxx: adding checks for failures]
> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> [imbrenda@xxxxxxxxxxxxx: adding a check for gmap fault]
> Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> [borntraeger@xxxxxxxxxx: patch merging, splitting, fixing]
> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> ---
> arch/s390/kernel/pgm_check.S | 4 +-
> arch/s390/mm/fault.c | 86 ++++++++++++++++++++++++++++++++++++
> 2 files changed, 88 insertions(+), 2 deletions(-)
>
> diff --git a/arch/s390/kernel/pgm_check.S b/arch/s390/kernel/pgm_check.S
> index 59dee9d3bebf..27ac4f324c70 100644
> --- a/arch/s390/kernel/pgm_check.S
> +++ b/arch/s390/kernel/pgm_check.S
> @@ -78,8 +78,8 @@ PGM_CHECK(do_dat_exception) /* 39 */
> PGM_CHECK(do_dat_exception) /* 3a */
> PGM_CHECK(do_dat_exception) /* 3b */
> PGM_CHECK_DEFAULT /* 3c */
> -PGM_CHECK_DEFAULT /* 3d */
> -PGM_CHECK_DEFAULT /* 3e */
> +PGM_CHECK(do_secure_storage_access) /* 3d */
> +PGM_CHECK(do_non_secure_storage_access) /* 3e */
> PGM_CHECK_DEFAULT /* 3f */
> PGM_CHECK_DEFAULT /* 40 */
> PGM_CHECK_DEFAULT /* 41 */
> diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
> index 7b0bb475c166..fab4219fa0be 100644
> --- a/arch/s390/mm/fault.c
> +++ b/arch/s390/mm/fault.c
> @@ -38,6 +38,7 @@
> #include <asm/irq.h>
> #include <asm/mmu_context.h>
> #include <asm/facility.h>
> +#include <asm/uv.h>
> #include "../kernel/entry.h"
>
> #define __FAIL_ADDR_MASK -4096L
> @@ -816,3 +817,88 @@ static int __init pfault_irq_init(void)
> early_initcall(pfault_irq_init);
>
> #endif /* CONFIG_PFAULT */
> +
> +#if IS_ENABLED(CONFIG_KVM)
> +void do_secure_storage_access(struct pt_regs *regs)
> +{
> + unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK;
> + struct vm_area_struct *vma;
> + struct mm_struct *mm;
> + struct page *page;
> + int rc;
> +
> + switch (get_fault_type(regs)) {
> + case USER_FAULT:
> + mm = current->mm;
> + down_read(&mm->mmap_sem);
> + vma = find_vma(mm, addr);
> + if (!vma) {
> + up_read(&mm->mmap_sem);
> + do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
> + break;
> + }
> + page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET);
> + if (IS_ERR_OR_NULL(page)) {
> + up_read(&mm->mmap_sem);
> + break;
> + }
> + if (arch_make_page_accessible(page))
> + send_sig(SIGSEGV, current, 0);
> + put_page(page);
> + up_read(&mm->mmap_sem);
> + break;
> + case KERNEL_FAULT:
> + page = phys_to_page(addr);
> + if (unlikely(!try_get_page(page)))
> + break;
> + rc = arch_make_page_accessible(page);
> + put_page(page);
> + if (rc)
> + BUG();
> + break;
> + case VDSO_FAULT:
> + /* fallthrough */
> + case GMAP_FAULT:
> + /* fallthrough */
Could we ever get here from the SIE?
> + default:
> + do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
> + WARN_ON_ONCE(1);
> + }
> +}
> +NOKPROBE_SYMBOL(do_secure_storage_access);
> +
> +void do_non_secure_storage_access(struct pt_regs *regs)
> +{
> + unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK;
> + struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
> + struct uv_cb_cts uvcb = {
> + .header.cmd = UVC_CMD_CONV_TO_SEC_STOR,
> + .header.len = sizeof(uvcb),
> + .guest_handle = gmap->guest_handle,
> + .gaddr = gaddr,
> + };
> + int rc;
> +
> + if (get_fault_type(regs) != GMAP_FAULT) {
> + do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
> + WARN_ON_ONCE(1);
> + return;
> + }
> +
> + rc = uv_make_secure(gmap, gaddr, &uvcb);
> + if (rc == -EINVAL && uvcb.header.rc != 0x104)
> + send_sig(SIGSEGV, current, 0);
Looks good to me, but I don't feel like being ready for an r-b. I'll
have to let that sink in :)
Assumed-is-okay-by: David Hildenbrand <david@xxxxxxxxxx>
--
Thanks,
David / dhildenb
