[Xen-devel] [PATCH v2] xen: support 52 bit physical addresses in pv guests

[Juergen Gross <jgross@xxxxxxxx>]

Physical addresses on processors supporting 5 level paging can be up to
52 bits wide. For a Xen pv guest running on such a machine those
physical addresses have to be supported in order to be able to use any
memory on the machine even if the guest itself does not support 5 level
paging.

So when reading/writing a MFN from/to a pte don't use the kernel's
PTE_PFN_MASK but a new XEN_PTE_MFN_MASK allowing full 40 bit wide MFNs.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V2:
- use __sme_clr() to clear any SME bit from MFN (Boris Ostrovsky)
---
 arch/x86/include/asm/xen/page.h | 11 ++++++++++-
 arch/x86/xen/mmu_pv.c           |  4 ++--
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index 07b6531813c4..90e91003fd9d 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -26,6 +26,15 @@ typedef struct xpaddr {
        phys_addr_t paddr;
 } xpaddr_t;
 
+#ifdef CONFIG_X86_64
+#define XEN_PHYSICAL_MASK      __sme_clr((1UL << 52) - 1)
+#else
+#define XEN_PHYSICAL_MASK      __PHYSICAL_MASK
+#endif
+
+#define XEN_PTE_MFN_MASK       ((pteval_t)(((signed long)PAGE_MASK) & \
+                                           XEN_PHYSICAL_MASK))
+
 #define XMADDR(x)      ((xmaddr_t) { .maddr = (x) })
 #define XPADDR(x)      ((xpaddr_t) { .paddr = (x) })
 
@@ -277,7 +286,7 @@ static inline unsigned long bfn_to_local_pfn(unsigned long 
mfn)
 
 static inline unsigned long pte_mfn(pte_t pte)
 {
-       return (pte.pte & PTE_PFN_MASK) >> PAGE_SHIFT;
+       return (pte.pte & XEN_PTE_MFN_MASK) >> PAGE_SHIFT;
 }
 
 static inline pte_t mfn_pte(unsigned long page_nr, pgprot_t pgprot)
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index 71495f1a86d7..9d9cc3870722 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -315,7 +315,7 @@ void xen_ptep_modify_prot_commit(struct mm_struct *mm, 
unsigned long addr,
 static pteval_t pte_mfn_to_pfn(pteval_t val)
 {
        if (val & _PAGE_PRESENT) {
-               unsigned long mfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
+               unsigned long mfn = (val & XEN_PTE_MFN_MASK) >> PAGE_SHIFT;
                unsigned long pfn = mfn_to_pfn(mfn);
 
                pteval_t flags = val & PTE_FLAGS_MASK;
@@ -1735,7 +1735,7 @@ static unsigned long __init m2p(phys_addr_t maddr)
 {
        phys_addr_t paddr;
 
-       maddr &= PTE_PFN_MASK;
+       maddr &= XEN_PTE_MFN_MASK;
        paddr = mfn_to_pfn(maddr >> PAGE_SHIFT) << PAGE_SHIFT;
 
        return paddr;
-- 
2.12.3


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