2022-03-25 15:35:17

by Thomas Gleixner

Subject: [patch 6/7] x86/fpu/xstate: Handle supervisor states in XSTATE permissions

The size calculation in __xstate_request_perm() fails to take supervisor
states into account because the permission bitmap is only relevant for user
states.

Up to 5.17 this does not matter because there are no supervisor states
supported, but the (re)enabling of ENQCMD makes them available.

Fixes: 7c1ef59145f1 ("x86/cpufeatures: Re-enable ENQCMD")
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: Tony Luck <[email protected]>
---
arch/x86/kernel/fpu/xstate.c | 3 +++
1 file changed, 3 insertions(+)

--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1566,6 +1566,9 @@ static int __xstate_request_perm(u64 per

/* Calculate the resulting kernel state size */
mask = permitted | requested;
+ /* Take supervisor states into account on the host */
+ if (!guest)
+ mask |= xfeatures_mask_supervisor();
ksize = xstate_calculate_size(mask, compacted);

/* Calculate the resulting user state size */

2022-03-31 22:12:07

by tip-bot2 for Alexey Makhalov

Subject: [tip: x86/urgent] x86/fpu/xstate: Handle supervisor states in XSTATE permissions

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID: 781c64bfcb735960717d1cb45428047ff6a5030c
Gitweb: https://git.kernel.org/tip/781c64bfcb735960717d1cb45428047ff6a5030c
Author: Thomas Gleixner <[email protected]>
AuthorDate: Thu, 24 Mar 2022 14:47:14 +01:00
Committer: Borislav Petkov <[email protected]>
CommitterDate: Wed, 30 Mar 2022 11:35:22 +02:00

x86/fpu/xstate: Handle supervisor states in XSTATE permissions

The size calculation in __xstate_request_perm() fails to take supervisor
states into account because the permission bitmap is only relevant for user
states.

Up to 5.17 this does not matter because there are no supervisor states
supported, but the (re-)enabling of ENQCMD makes them available.

Fixes: 7c1ef59145f1 ("x86/cpufeatures: Re-enable ENQCMD")
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
arch/x86/kernel/fpu/xstate.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index c55f72e..5ac934b 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1571,6 +1571,9 @@ static int __xstate_request_perm(u64 permitted, u64 requested, bool guest)

/* Calculate the resulting kernel state size */
mask = permitted | requested;
+ /* Take supervisor states into account on the host */
+ if (!guest)
+ mask |= xfeatures_mask_supervisor();
ksize = xstate_calculate_size(mask, compacted);

/* Calculate the resulting user state size */