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Subject[PATCHv7 17/19] x86/xen: Allow XEN_PV and XEN_PVH to be enabled with X86_5LEVEL
Date
With boot-time switching between paging modes, XEN_PV and XEN_PVH can be
boot into 4-level paging mode.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Tested-by: Juergen Gross <jgross@suse.com>
---
arch/x86/kernel/head_64.S | 12 ++++++------
arch/x86/xen/Kconfig | 5 -----
arch/x86/xen/mmu_pv.c | 21 +++++++++++++++++++++
3 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 49f8bb43d107..e137f2665fc2 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -37,12 +37,12 @@
*
*/

+#define l4_index(x) (((x) >> 39) & 511)
#define pud_index(x) (((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))

-#if defined(CONFIG_XEN_PV) || defined(CONFIG_XEN_PVH)
-PGD_PAGE_OFFSET = pgd_index(__PAGE_OFFSET_BASE48)
-PGD_START_KERNEL = pgd_index(__START_KERNEL_map)
-#endif
+L4_PAGE_OFFSET = l4_index(__PAGE_OFFSET_BASE48)
+L4_START_KERNEL = l4_index(__START_KERNEL_map)
+
L3_START_KERNEL = pud_index(__START_KERNEL_map)

.text
@@ -363,9 +363,9 @@ NEXT_PAGE(early_dynamic_pgts)
#if defined(CONFIG_XEN_PV) || defined(CONFIG_XEN_PVH)
NEXT_PAGE(init_top_pgt)
.quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
- .org init_top_pgt + PGD_PAGE_OFFSET*8, 0
+ .org init_top_pgt + L4_PAGE_OFFSET*8, 0
.quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
- .org init_top_pgt + PGD_START_KERNEL*8, 0
+ .org init_top_pgt + L4_START_KERNEL*8, 0
/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
.quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC

diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
index 1ecd419811a2..027987638e98 100644
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -17,9 +17,6 @@ config XEN_PV
bool "Xen PV guest support"
default y
depends on XEN
- # XEN_PV is not ready to work with 5-level paging.
- # Changes to hypervisor are also required.
- depends on !X86_5LEVEL
select XEN_HAVE_PVMMU
select XEN_HAVE_VPMU
help
@@ -78,6 +75,4 @@ config XEN_DEBUG_FS
config XEN_PVH
bool "Support for running as a PVH guest"
depends on XEN && XEN_PVHVM && ACPI
- # Pre-built page tables are not ready to handle 5-level paging.
- depends on !X86_5LEVEL
def_bool n
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index 5811815cc6ef..e81bf881847f 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -538,6 +538,22 @@ static void xen_set_p4d(p4d_t *ptr, p4d_t val)

xen_mc_issue(PARAVIRT_LAZY_MMU);
}
+
+#if CONFIG_PGTABLE_LEVELS >= 5
+__visible p4dval_t xen_p4d_val(p4d_t p4d)
+{
+ return pte_mfn_to_pfn(p4d.p4d);
+}
+PV_CALLEE_SAVE_REGS_THUNK(xen_p4d_val);
+
+__visible p4d_t xen_make_p4d(p4dval_t p4d)
+{
+ p4d = pte_pfn_to_mfn(p4d);
+
+ return native_make_p4d(p4d);
+}
+PV_CALLEE_SAVE_REGS_THUNK(xen_make_p4d);
+#endif /* CONFIG_PGTABLE_LEVELS >= 5 */
#endif /* CONFIG_X86_64 */

static int xen_pmd_walk(struct mm_struct *mm, pmd_t *pmd,
@@ -2408,6 +2424,11 @@ static const struct pv_mmu_ops xen_mmu_ops __initconst = {

.alloc_pud = xen_alloc_pmd_init,
.release_pud = xen_release_pmd_init,
+
+#if CONFIG_PGTABLE_LEVELS >= 5
+ .p4d_val = PV_CALLEE_SAVE(xen_p4d_val),
+ .make_p4d = PV_CALLEE_SAVE(xen_make_p4d),
+#endif
#endif /* CONFIG_X86_64 */

.activate_mm = xen_activate_mm,
--
2.14.1
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