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Re: [Xen-devel] [PATCH v6 10/34] x86, x86/mm, x86/xen, olpc: Use __va() against just the physical address in cr3
- To: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, linux-arch@xxxxxxxxxxxxxxx, linux-efi@xxxxxxxxxxxxxxx, kvm@xxxxxxxxxxxxxxx, linux-doc@xxxxxxxxxxxxxxx, x86@xxxxxxxxxx, kexec@xxxxxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, kasan-dev@xxxxxxxxxxxxxxxx, linux-mm@xxxxxxxxx, iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
- From: Tom Lendacky <thomas.lendacky@xxxxxxx>
- Date: Thu, 8 Jun 2017 08:42:51 -0500
- Cc: Brijesh Singh <brijesh.singh@xxxxxxx>, Toshimitsu Kani <toshi.kani@xxxxxxx>, Radim Krčmář <rkrcmar@xxxxxxxxxx>, Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>, Alexander Potapenko <glider@xxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Larry Woodman <lwoodman@xxxxxxxxxx>, Jonathan Corbet <corbet@xxxxxxx>, Joerg Roedel <joro@xxxxxxxxxx>, "Michael S. Tsirkin" <mst@xxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>, Dave Young <dyoung@xxxxxxxxxx>, Rik van Riel <riel@xxxxxxxxxx>, Arnd Bergmann <arnd@xxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, Andy Lutomirski <luto@xxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Dmitry Vyukov <dvyukov@xxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxx>, Paolo Bonzini <pbonzini@xxxxxxxxxx>
- Delivery-date: Thu, 08 Jun 2017 13:43:17 +0000
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
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On 6/7/2017 5:06 PM, Boris Ostrovsky wrote:
On 06/07/2017 03:14 PM, Tom Lendacky wrote:
The cr3 register entry can contain the SME encryption bit that indicates
the PGD is encrypted. The encryption bit should not be used when creating
a virtual address for the PGD table.
Create a new function, read_cr3_pa(), that will extract the physical
address from the cr3 register. This function is then used where a virtual
address of the PGD needs to be created/used from the cr3 register.
Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
---
arch/x86/include/asm/special_insns.h | 9 +++++++++
arch/x86/kernel/head64.c | 2 +-
arch/x86/mm/fault.c | 10 +++++-----
arch/x86/mm/ioremap.c | 2 +-
arch/x86/platform/olpc/olpc-xo1-pm.c | 2 +-
arch/x86/power/hibernate_64.c | 2 +-
arch/x86/xen/mmu_pv.c | 6 +++---
7 files changed, 21 insertions(+), 12 deletions(-)
...
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index 1f386d7..2dc5243 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -2022,7 +2022,7 @@ static phys_addr_t __init xen_early_virt_to_phys(unsigned
long vaddr)
pmd_t pmd;
pte_t pte;
- pa = read_cr3();
+ pa = read_cr3_pa();
pgd = native_make_pgd(xen_read_phys_ulong(pa + pgd_index(vaddr) *
sizeof(pgd)));
if (!pgd_present(pgd))
@@ -2102,7 +2102,7 @@ void __init xen_relocate_p2m(void)
pt_phys = pmd_phys + PFN_PHYS(n_pmd);
p2m_pfn = PFN_DOWN(pt_phys) + n_pt;
- pgd = __va(read_cr3());
+ pgd = __va(read_cr3_pa());
new_p2m = (unsigned long *)(2 * PGDIR_SIZE);
idx_p4d = 0;
save_pud = n_pud;
@@ -2209,7 +2209,7 @@ static void __init xen_write_cr3_init(unsigned long cr3)
{
unsigned long pfn = PFN_DOWN(__pa(swapper_pg_dir));
- BUG_ON(read_cr3() != __pa(initial_page_table));
+ BUG_ON(read_cr3_pa() != __pa(initial_page_table));
BUG_ON(cr3 != __pa(swapper_pg_dir));
/*
(Please copy Xen maintainers when modifying xen-related files.)
Sorry about that, missed adding the Xen maintainers when I added this
change.
Given that page tables for Xen PV guests are controlled by the
hypervisor I don't think this change (although harmless) is necessary.
I can back this change out if the Xen maintainers think that's best.
What may be needed is making sure X86_FEATURE_SME is not set for PV guests.
And that may be something that Xen will need to control through either
CPUID or MSR support for the PV guests.
Thanks,
Tom
-boris
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