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Message-Id: <20170214194259.75960-4-thgarnie@google.com>
Date: Tue, 14 Feb 2017 11:42:59 -0800
From: Thomas Garnier <thgarnie@...gle.com>
To: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H . Peter Anvin" <hpa@...or.com>,
Andrey Ryabinin <aryabinin@...tuozzo.com>,
Alexander Potapenko <glider@...gle.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Thomas Garnier <thgarnie@...gle.com>,
Kees Cook <keescook@...omium.org>,
Andy Lutomirski <luto@...nel.org>,
Borislav Petkov <bp@...e.de>,
Paul Gortmaker <paul.gortmaker@...driver.com>,
Andy Lutomirski <luto@...capital.net>,
"Rafael J . Wysocki" <rjw@...ysocki.net>,
Len Brown <len.brown@...el.com>,
Pavel Machek <pavel@....cz>,
Jiri Kosina <jikos@...nel.org>,
Matt Fleming <matt@...eblueprint.co.uk>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Juergen Gross <jgross@...e.com>,
Rusty Russell <rusty@...tcorp.com.au>,
Peter Zijlstra <peterz@...radead.org>,
Christian Borntraeger <borntraeger@...ibm.com>,
"Luis R . Rodriguez" <mcgrof@...nel.org>,
He Chen <he.chen@...ux.intel.com>,
Brian Gerst <brgerst@...il.com>,
Stanislaw Gruszka <sgruszka@...hat.com>,
Arnd Bergmann <arnd@...db.de>,
Adam Buchbinder <adam.buchbinder@...il.com>,
Dave Hansen <dave.hansen@...el.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Tim Chen <tim.c.chen@...ux.intel.com>,
Rik van Riel <riel@...hat.com>,
Andi Kleen <ak@...ux.intel.com>,
Jiri Olsa <jolsa@...hat.com>,
Michael Ellerman <mpe@...erman.id.au>,
Joerg Roedel <joro@...tes.org>,
Paolo Bonzini <pbonzini@...hat.com>,
Radim Krčmář <rkrcmar@...hat.com>
Cc: x86@...nel.org,
linux-kernel@...r.kernel.org,
kasan-dev@...glegroups.com,
linux-pm@...r.kernel.org,
linux-efi@...r.kernel.org,
xen-devel@...ts.xenproject.org,
lguest@...ts.ozlabs.org,
kvm@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCH v3 4/4] KVM: VMX: Simplify segment_base
The KVM segment_base function is confusing. This patch replaces integers
with appropriate flags, simplify constructs and add comments.
Signed-off-by: Thomas Garnier <thgarnie@...gle.com>
---
Based on next-20170213
---
arch/x86/kvm/vmx.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 99167f20bc34..edb8326108dd 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2062,25 +2062,35 @@ static unsigned long segment_base(u16 selector)
struct desc_struct *d;
unsigned long table_base;
unsigned long v;
+ u32 high32;
- if (!(selector & ~3))
+ if (!(selector & ~SEGMENT_RPL_MASK))
return 0;
- table_base = get_current_gdt_rw_vaddr();
-
- if (selector & 4) { /* from ldt */
+ /* LDT selector */
+ if ((selector & SEGMENT_TI_MASK) == SEGMENT_LDT) {
u16 ldt_selector = kvm_read_ldt();
- if (!(ldt_selector & ~3))
+ if (!(ldt_selector & ~SEGMENT_RPL_MASK))
return 0;
table_base = segment_base(ldt_selector);
+ } else {
+ table_base = get_current_gdt_rw_vaddr();
}
- d = (struct desc_struct *)(table_base + (selector & ~7));
+
+ d = (struct desc_struct *)table_base + (selector >> 3);
v = get_desc_base(d);
#ifdef CONFIG_X86_64
- if (d->s == 0 && (d->type == 2 || d->type == 9 || d->type == 11))
- v |= ((unsigned long)((struct ldttss_desc64 *)d)->base3) << 32;
+ /*
+ * Extend the virtual address if we have a system descriptor entry for
+ * LDT or TSS (available or busy).
+ */
+ if (d->s == 0 && (d->type == DESC_LDT || d->type == DESC_TSS ||
+ d->type == 11/*Busy TSS */)) {
+ high32 = ((struct ldttss_desc64 *)d)->base3;
+ v |= (u64)high32 << 32;
+ }
#endif
return v;
}
--
2.11.0.483.g087da7b7c-goog
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