All of lore.kernel.org
 help / color / mirror / Atom feed
From: Juergen Gross <jgross@suse.com>
To: linux-kernel@vger.kernel.org, x86@kernel.org
Cc: Juergen Gross <jgross@suse.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH v4 12/12] x86/mm: only check uniform after calling mtrr_type_lookup()
Date: Mon,  6 Mar 2023 17:34:25 +0100	[thread overview]
Message-ID: <20230306163425.8324-13-jgross@suse.com> (raw)
In-Reply-To: <20230306163425.8324-1-jgross@suse.com>

Today pud_set_huge() and pmd_set_huge() test for the MTRR type to be
WB or INVALID after calling mtrr_type_lookup(). Those tests can be
dropped, as the only reason to not use a large mapping would be
uniform being 0. Any MTRR type can be accepted as long as it applies
to the whole memory range covered by the mapping, as the alternative
would only be to map the same region with smaller pages instead, using
the same PAT type as for the large mapping.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
V3:
- adapt comment for pud_set_huge()
---
 arch/x86/mm/pgtable.c | 24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index e4f499eb0f29..15a8009a4480 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -702,14 +702,8 @@ void p4d_clear_huge(p4d_t *p4d)
  * pud_set_huge - setup kernel PUD mapping
  *
  * MTRRs can override PAT memory types with 4KiB granularity. Therefore, this
- * function sets up a huge page only if any of the following conditions are met:
- *
- * - MTRRs are disabled, or
- *
- * - MTRRs are enabled and the range is completely covered by a single MTRR, or
- *
- * - MTRRs are enabled and the corresponding MTRR memory type is WB, which
- *   has no effect on the requested PAT memory type.
+ * function sets up a huge page only if the complete range has the same MTRR
+ * caching mode.
  *
  * Callers should try to decrease page size (1GB -> 2MB -> 4K) if the bigger
  * page mapping attempt fails.
@@ -718,11 +712,10 @@ void p4d_clear_huge(p4d_t *p4d)
  */
 int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
 {
-	u8 mtrr, uniform;
+	u8 uniform;
 
-	mtrr = mtrr_type_lookup(addr, addr + PUD_SIZE, &uniform);
-	if ((mtrr != MTRR_TYPE_INVALID) && (!uniform) &&
-	    (mtrr != MTRR_TYPE_WRBACK))
+	mtrr_type_lookup(addr, addr + PUD_SIZE, &uniform);
+	if (!uniform)
 		return 0;
 
 	/* Bail out if we are we on a populated non-leaf entry: */
@@ -745,11 +738,10 @@ int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
  */
 int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
 {
-	u8 mtrr, uniform;
+	u8 uniform;
 
-	mtrr = mtrr_type_lookup(addr, addr + PMD_SIZE, &uniform);
-	if ((mtrr != MTRR_TYPE_INVALID) && (!uniform) &&
-	    (mtrr != MTRR_TYPE_WRBACK)) {
+	mtrr_type_lookup(addr, addr + PMD_SIZE, &uniform);
+	if (!uniform) {
 		pr_warn_once("%s: Cannot satisfy [mem %#010llx-%#010llx] with a huge-page mapping due to MTRR override.\n",
 			     __func__, addr, addr + PMD_SIZE);
 		return 0;
-- 
2.35.3


  parent reply	other threads:[~2023-03-06 16:37 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-06 16:34 [PATCH v4 00/12] x86/mtrr: fix handling with PAT but without MTRR Juergen Gross
2023-03-06 16:34 ` [PATCH v4 01/12] x86/mtrr: split off physical address size calculation Juergen Gross
2023-03-06 16:34 ` [PATCH v4 02/12] x86/mtrr: optimize mtrr_calc_physbits() Juergen Gross
2023-03-20 12:50   ` Borislav Petkov
2023-03-06 16:34 ` [PATCH v4 03/12] x86/mtrr: support setting MTRR state for software defined MTRRs Juergen Gross
2023-03-20 12:59   ` Huang, Kai
2023-03-20 13:47     ` Juergen Gross
2023-03-20 21:34       ` Huang, Kai
2023-03-20 22:42       ` Borislav Petkov
2023-03-21  6:01         ` Juergen Gross
2023-03-20 19:05   ` Borislav Petkov
2023-03-21  6:00     ` Juergen Gross
2023-03-21 10:30       ` Borislav Petkov
2023-03-21 15:49         ` Juergen Gross
2023-03-06 16:34 ` [PATCH v4 04/12] x86/hyperv: set MTRR state when running as SEV-SNP Hyper-V guest Juergen Gross
2023-03-06 16:34 ` [PATCH v4 05/12] x86/xen: set MTRR state when running as Xen PV initial domain Juergen Gross
2023-03-07 21:47   ` Boris Ostrovsky
2023-03-23 12:43   ` Borislav Petkov
2023-03-06 16:34 ` [PATCH v4 06/12] x86/mtrr: replace vendor tests in MTRR code Juergen Gross
2023-03-24 16:56   ` Borislav Petkov
2023-03-27  5:43     ` Juergen Gross
2023-03-27  7:14       ` Borislav Petkov
2023-03-06 16:34 ` [PATCH v4 07/12] x86/mtrr: allocate mtrr_value array dynamically Juergen Gross
2023-03-20 12:25   ` Huang, Kai
2023-03-20 13:49     ` Juergen Gross
2023-03-20 15:31       ` Dave Hansen
2023-03-20 15:49         ` Juergen Gross
2023-03-26 22:05   ` Borislav Petkov
2023-03-27  5:44     ` Juergen Gross
2023-03-06 16:34 ` [PATCH v4 08/12] x86/mtrr: add get_effective_type() service function Juergen Gross
2023-03-06 16:34 ` [PATCH v4 09/12] x86/mtrr: construct a memory map with cache modes Juergen Gross
2023-03-29 12:51   ` Borislav Petkov
2023-03-29 13:39     ` Juergen Gross
2023-03-31 12:55       ` Borislav Petkov
2023-03-31 13:23         ` Juergen Gross
2023-04-01 14:24           ` Borislav Petkov
2023-04-03  6:57             ` Juergen Gross
2023-03-31 12:57   ` Borislav Petkov
2023-03-31 13:35     ` Juergen Gross
2023-04-01 14:26       ` Borislav Petkov
2023-04-03  7:02         ` Juergen Gross
2023-03-06 16:34 ` [PATCH v4 10/12] x86/mtrr: use new cache_map in mtrr_type_lookup() Juergen Gross
2023-03-06 16:34 ` [PATCH v4 11/12] x86/mtrr: don't let mtrr_type_lookup() return MTRR_TYPE_INVALID Juergen Gross
2023-03-06 16:34 ` Juergen Gross [this message]
2023-03-07 21:09 ` [PATCH v4 00/12] x86/mtrr: fix handling with PAT but without MTRR Michael Kelley (LINUX)

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20230306163425.8324-13-jgross@suse.com \
    --to=jgross@suse.com \
    --cc=bp@alien8.de \
    --cc=dave.hansen@linux.intel.com \
    --cc=hpa@zytor.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=torvalds@linux-foundation.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.