[PATCH V3 3/3] Support Xen pv-domains using PAT
From: Juergen Gross
Date: Fri Sep 12 2014 - 06:36:14 EST
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>
---
arch/x86/xen/enlighten.c | 25 +++++++------------------
arch/x86/xen/mmu.c | 48 ++----------------------------------------------
arch/x86/xen/xen-ops.h | 1 -
3 files changed, 9 insertions(+), 65 deletions(-)
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index c0cb11f..75ac572 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);
@@ -1554,10 +1548,6 @@ 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);
__supported_pte_mask |= _PAGE_IOMAP;
@@ -1613,14 +1603,6 @@ 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];
@@ -1634,6 +1616,13 @@ asmlinkage __visible void __init xen_start_kernel(void)
/* Allocate and initialize top and mid mfn levels for p2m structure */
xen_build_mfn_list_list();
+ /*
+ * 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 e8a1201..70702e9 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -434,13 +434,7 @@ static pteval_t iomap_pte(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
+
if (xen_initial_domain() && (pteval & _PAGE_IOMAP))
return pteval;
@@ -454,48 +448,10 @@ __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)
{
phys_addr_t addr = (pte & PTE_PFN_MASK);
-#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
+
/*
* Unprivileged domains are allowed to do IOMAPpings for
* PCI passthrough, but not map ISA space. The ISA
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);
--
1.8.4.5
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/