[tip:x86/mm] xen: Support Xen pv-domains using PAT
From: tip-bot for Juergen Gross
Date: Sun Nov 16 2014 - 05:59:34 EST
Commit-ID: 47591df505129c9774af6cca2debf283a6e56ed7
Gitweb: http://git.kernel.org/tip/47591df505129c9774af6cca2debf283a6e56ed7
Author: Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Mon, 3 Nov 2014 14:02:04 +0100
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Sun, 16 Nov 2014 11:04:26 +0100
xen: Support Xen pv-domains using PAT
With the dynamical mapping between cache modes and pgprot values it is
now possible to use all cache modes via the Xen hypervisor PAT settings
in a pv domain.
All to be done is to read the PAT configuration MSR and set up the
translation tables accordingly.
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stefan.bader@xxxxxxxxxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Cc: ville.syrjala@xxxxxxxxxxxxxxx
Cc: jbeulich@xxxxxxxx
Cc: toshi.kani@xxxxxx
Cc: plagnioj@xxxxxxxxxxxx
Cc: tomi.valkeinen@xxxxxx
Cc: bhelgaas@xxxxxxxxxx
Link: http://lkml.kernel.org/r/1415019724-4317-19-git-send-email-jgross@xxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/x86/xen/enlighten.c | 25 +++++++------------------
arch/x86/xen/mmu.c | 47 +----------------------------------------------
arch/x86/xen/xen-ops.h | 1 -
3 files changed, 8 insertions(+), 65 deletions(-)
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index fac5e4f..6bf3a13 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1100,12 +1100,6 @@ static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)
/* Fast syscall setup is all done in hypercalls, so
these are all ignored. Stub them out here to stop
Xen console noise. */
- break;
-
- case MSR_IA32_CR_PAT:
- if (smp_processor_id() == 0)
- xen_set_pat(((u64)high << 32) | low);
- break;
default:
ret = native_write_msr_safe(msr, low, high);
@@ -1561,10 +1555,6 @@ asmlinkage __visible void __init xen_start_kernel(void)
/* Prevent unwanted bits from being set in PTEs. */
__supported_pte_mask &= ~_PAGE_GLOBAL;
-#if 0
- if (!xen_initial_domain())
-#endif
- __supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD);
/*
* Prevent page tables from being allocated in highmem, even
@@ -1618,14 +1608,6 @@ asmlinkage __visible void __init xen_start_kernel(void)
*/
acpi_numa = -1;
#endif
-#ifdef CONFIG_X86_PAT
- /*
- * For right now disable the PAT. We should remove this once
- * git commit 8eaffa67b43e99ae581622c5133e20b0f48bcef1
- * (xen/pat: Disable PAT support for now) is reverted.
- */
- pat_enabled = 0;
-#endif
/* Don't do the full vcpu_info placement stuff until we have a
possible map and a non-dummy shared_info. */
per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
@@ -1636,6 +1618,13 @@ asmlinkage __visible void __init xen_start_kernel(void)
xen_raw_console_write("mapping kernel into physical memory\n");
xen_setup_kernel_pagetable((pgd_t *)xen_start_info->pt_base, xen_start_info->nr_pages);
+ /*
+ * Modify the cache mode translation tables to match Xen's PAT
+ * configuration.
+ */
+
+ pat_init_cache_modes();
+
/* keep using Xen gdt for now; no urgent need to change it */
#ifdef CONFIG_X86_32
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index a8a1a3d..9855eb8 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -410,13 +410,7 @@ static pteval_t pte_pfn_to_mfn(pteval_t val)
__visible pteval_t xen_pte_val(pte_t pte)
{
pteval_t pteval = pte.pte;
-#if 0
- /* If this is a WC pte, convert back from Xen WC to Linux WC */
- if ((pteval & (_PAGE_PAT | _PAGE_PCD | _PAGE_PWT)) == _PAGE_PAT) {
- WARN_ON(!pat_enabled);
- pteval = (pteval & ~_PAGE_PAT) | _PAGE_PWT;
- }
-#endif
+
return pte_mfn_to_pfn(pteval);
}
PV_CALLEE_SAVE_REGS_THUNK(xen_pte_val);
@@ -427,47 +421,8 @@ __visible pgdval_t xen_pgd_val(pgd_t pgd)
}
PV_CALLEE_SAVE_REGS_THUNK(xen_pgd_val);
-/*
- * Xen's PAT setup is part of its ABI, though I assume entries 6 & 7
- * are reserved for now, to correspond to the Intel-reserved PAT
- * types.
- *
- * We expect Linux's PAT set as follows:
- *
- * Idx PTE flags Linux Xen Default
- * 0 WB WB WB
- * 1 PWT WC WT WT
- * 2 PCD UC- UC- UC-
- * 3 PCD PWT UC UC UC
- * 4 PAT WB WC WB
- * 5 PAT PWT WC WP WT
- * 6 PAT PCD UC- rsv UC-
- * 7 PAT PCD PWT UC rsv UC
- */
-
-void xen_set_pat(u64 pat)
-{
- /* We expect Linux to use a PAT setting of
- * UC UC- WC WB (ignoring the PAT flag) */
- WARN_ON(pat != 0x0007010600070106ull);
-}
-
__visible pte_t xen_make_pte(pteval_t pte)
{
-#if 0
- /* If Linux is trying to set a WC pte, then map to the Xen WC.
- * If _PAGE_PAT is set, then it probably means it is really
- * _PAGE_PSE, so avoid fiddling with the PAT mapping and hope
- * things work out OK...
- *
- * (We should never see kernel mappings with _PAGE_PSE set,
- * but we could see hugetlbfs mappings, I think.).
- */
- if (pat_enabled && !WARN_ON(pte & _PAGE_PAT)) {
- if ((pte & (_PAGE_PCD | _PAGE_PWT)) == _PAGE_PWT)
- pte = (pte & ~(_PAGE_PCD | _PAGE_PWT)) | _PAGE_PAT;
- }
-#endif
pte = pte_pfn_to_mfn(pte);
return native_make_pte(pte);
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 28c7e0b..4ab9298 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -33,7 +33,6 @@ extern unsigned long xen_max_p2m_pfn;
void xen_mm_pin_all(void);
void xen_mm_unpin_all(void);
-void xen_set_pat(u64);
char * __init xen_memory_setup(void);
char * xen_auto_xlated_memory_setup(void);
--
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