From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752933AbaHSN0D (ORCPT ); Tue, 19 Aug 2014 09:26:03 -0400 Received: from cantor2.suse.de ([195.135.220.15]:52345 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750870AbaHSN0A (ORCPT ); Tue, 19 Aug 2014 09:26:00 -0400 From: jgross@suse.com To: stefan.bader@canonical.com, toshi.kani@hp.com, linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com, konrad.wilk@oracle.com, ville.syrjala@linux.intel.com, hpa@zytor.com, x86@kernel.org Cc: Juergen Gross Subject: [PATCH RFC 3/3] Support Xen pv-domains using PAT Date: Tue, 19 Aug 2014 15:25:45 +0200 Message-Id: <1408454745-32358-4-git-send-email-jgross@suse.com> X-Mailer: git-send-email 1.8.4.5 In-Reply-To: <1408454745-32358-1-git-send-email-jgross@suse.com> References: <1408454745-32358-1-git-send-email-jgross@suse.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Juergen Gross 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 --- arch/x86/xen/enlighten.c | 12 ++++++---- arch/x86/xen/mmu.c | 60 +++++++++++++++++------------------------------- arch/x86/xen/xen-ops.h | 1 + 3 files changed, 30 insertions(+), 43 deletions(-) diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index c0cb11f..ef705a3 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -1552,12 +1552,16 @@ asmlinkage __visible void __init xen_start_kernel(void) xen_init_mmu_ops(); + /* + * Modify the cache mode translation tables to match Xen's PAT + * configuration. + */ + + if (xen_init_cache_types()) + __supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD); + /* 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; diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index e8a1201..49830c0 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; @@ -455,47 +449,35 @@ __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 + * Xen's PAT setup is part of its ABI. + * We don't care what Linux wants to use, just fall back to the Xen PAT + * configuration. All we have to do in case of a Linux's PAT configuration + * is to overwrite the cache mode translation tables with the correct + * values for the Xen configuration. */ +int xen_init_cache_types(void) +{ + u64 pat; + int err; + + err = rdmsrl_safe(MSR_IA32_CR_PAT, &pat); + if (!err) + pat_init_cache_modes(pat); + return err; +} + 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); + if (xen_init_cache_types()) + /* Domain configured PAT, but we can't adapt to the changes */ + BUG(); } __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..da7e666 100644 --- a/arch/x86/xen/xen-ops.h +++ b/arch/x86/xen/xen-ops.h @@ -34,6 +34,7 @@ extern unsigned long xen_max_p2m_pfn; void xen_mm_pin_all(void); void xen_mm_unpin_all(void); void xen_set_pat(u64); +int xen_init_cache_types(void); char * __init xen_memory_setup(void); char * xen_auto_xlated_memory_setup(void); -- 1.8.4.5