提交 41f2e477 编写于 作者: J Jeremy Fitzhardinge

xen: add support for PAT

Convert Linux PAT entries into Xen ones when constructing ptes.  Linux
doesn't use _PAGE_PAT for ptes, so the only difference in the first 4
entries is that Linux uses _PAGE_PWT for WC, whereas Xen (and default)
use it for WT.

xen_pte_val does the inverse conversion.

We hard-code assumptions about Linux's current PAT layout, but a
warning on the wrmsr to MSR_IA32_CR_PAT should point out any problems.
If necessary we could go to a more general table-based conversion between
Linux and Xen PAT entries.

hugetlbfs poses a problem at the moment, the x86 architecture uses the
same flag for _PAGE_PAT and _PAGE_PSE, which changes meaning depending
on which pagetable level we're using.  At the moment this should be OK
so long as nobody tries to do a pte_val on a hugetlbfs pte.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
上级 2f7acb20
......@@ -829,6 +829,11 @@ static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)
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);
}
......
......@@ -55,6 +55,7 @@
#include <asm/e820.h>
#include <asm/linkage.h>
#include <asm/page.h>
#include <asm/pat.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>
......@@ -780,10 +781,18 @@ static pteval_t iomap_pte(pteval_t val)
pteval_t xen_pte_val(pte_t pte)
{
if (xen_initial_domain() && (pte.pte & _PAGE_IOMAP))
return pte.pte;
pteval_t pteval = pte.pte;
return pte_mfn_to_pfn(pte.pte);
/* 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;
}
if (xen_initial_domain() && (pteval & _PAGE_IOMAP))
return pteval;
return pte_mfn_to_pfn(pteval);
}
PV_CALLEE_SAVE_REGS_THUNK(xen_pte_val);
......@@ -793,10 +802,48 @@ 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- UC UC-
* 7 PAT PCD PWT UC UC 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);
}
pte_t xen_make_pte(pteval_t pte)
{
phys_addr_t addr = (pte & PTE_PFN_MASK);
/* 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;
}
/*
* Unprivileged domains are allowed to do IOMAPpings for
* PCI passthrough, but not map ISA space. The ISA
......
......@@ -32,6 +32,8 @@ void xen_ident_map_ISA(void);
void xen_reserve_top(void);
extern unsigned long xen_max_p2m_pfn;
void xen_set_pat(u64);
char * __init xen_memory_setup(void);
void __init xen_arch_setup(void);
void __init xen_init_IRQ(void);
......
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