diff options
Diffstat (limited to '0034-x86-cpuid-Fix-handling-of-XSAVE-dynamic-leaves.patch')
| -rw-r--r-- | 0034-x86-cpuid-Fix-handling-of-XSAVE-dynamic-leaves.patch | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/0034-x86-cpuid-Fix-handling-of-XSAVE-dynamic-leaves.patch b/0034-x86-cpuid-Fix-handling-of-XSAVE-dynamic-leaves.patch new file mode 100644 index 0000000..1905728 --- /dev/null +++ b/0034-x86-cpuid-Fix-handling-of-XSAVE-dynamic-leaves.patch @@ -0,0 +1,72 @@ +From 9b43092d54b5f9e9d39d9f20393671e303b19e81 Mon Sep 17 00:00:00 2001 +From: Andrew Cooper <andrew.cooper3@citrix.com> +Date: Wed, 26 Jun 2024 13:43:44 +0200 +Subject: [PATCH 34/56] x86/cpuid: Fix handling of XSAVE dynamic leaves + +[ This is a minimal backport of commit 71cacfb035f4 ("x86/cpuid: Fix handling + of XSAVE dynamic leaves") to fix the bugs without depending on the large + rework of XSTATE handling in Xen 4.19 ] + +First, if XSAVE is available in hardware but not visible to the guest, the +dynamic leaves shouldn't be filled in. + +Second, the comment concerning XSS state is wrong. VT-x doesn't manage +host/guest state automatically, but there is provision for "host only" bits to +be set, so the implications are still accurate. + +In Xen 4.18, no XSS states are supported, so it's safe to keep deferring to +real hardware. + +Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> +Reviewed-by: Jan Beulich <jbeulich@suse.com> +master commit: 71cacfb035f4a78ee10970dc38a3baa04d387451 +master date: 2024-06-19 13:00:06 +0100 +--- + xen/arch/x86/cpuid.c | 30 +++++++++++++----------------- + 1 file changed, 13 insertions(+), 17 deletions(-) + +diff --git a/xen/arch/x86/cpuid.c b/xen/arch/x86/cpuid.c +index 455a09b2dd..f6fd6cc6b3 100644 +--- a/xen/arch/x86/cpuid.c ++++ b/xen/arch/x86/cpuid.c +@@ -330,24 +330,20 @@ void guest_cpuid(const struct vcpu *v, uint32_t leaf, + case XSTATE_CPUID: + switch ( subleaf ) + { +- case 1: +- if ( p->xstate.xsavec || p->xstate.xsaves ) +- { +- /* +- * TODO: Figure out what to do for XSS state. VT-x manages +- * host vs guest MSR_XSS automatically, so as soon as we start +- * supporting any XSS states, the wrong XSS will be in +- * context. +- */ +- BUILD_BUG_ON(XSTATE_XSAVES_ONLY != 0); +- +- /* +- * Read CPUID[0xD,0/1].EBX from hardware. They vary with +- * enabled XSTATE, and appropraite XCR0|XSS are in context. +- */ ++ /* ++ * Read CPUID[0xd,0/1].EBX from hardware. They vary with enabled ++ * XSTATE, and the appropriate XCR0 is in context. ++ */ + case 0: +- res->b = cpuid_count_ebx(leaf, subleaf); +- } ++ if ( p->basic.xsave ) ++ res->b = cpuid_count_ebx(0xd, 0); ++ break; ++ ++ case 1: ++ /* This only works because Xen doesn't support XSS states yet. */ ++ BUILD_BUG_ON(XSTATE_XSAVES_ONLY != 0); ++ if ( p->xstate.xsavec ) ++ res->b = cpuid_count_ebx(0xd, 1); + break; + } + break; +-- +2.45.2 + |