diff options
| author | Juergen Gross <jgross@suse.com> | 2022-09-26 13:16:56 +0200 |
|---|---|---|
| committer | Juergen Gross <jgross@suse.com> | 2022-10-11 10:51:05 +0200 |
| commit | 3fac3734c43a2e21fefeb72124d8bd31dff3956f (patch) | |
| tree | d500099e8e4eb012db4510dfaf17da126f3156df /arch/x86 | |
| parent | a1886b915e81439ba045b1431f3319d37ac1b906 (diff) | |
xen/pv: support selecting safe/unsafe msr accesses
Instead of always doing the safe variants for reading and writing MSRs
in Xen PV guests, make the behavior controllable via Kconfig option
and a boot parameter.
The default will be the current behavior, which is to always use the
safe variant.
Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/xen/Kconfig | 9 | ||||
| -rw-r--r-- | arch/x86/xen/enlighten_pv.c | 24 |
2 files changed, 23 insertions, 10 deletions
diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig index 85246dd9faa1..9b1ec5d8c99c 100644 --- a/arch/x86/xen/Kconfig +++ b/arch/x86/xen/Kconfig @@ -92,3 +92,12 @@ config XEN_DOM0 select X86_X2APIC if XEN_PVH && X86_64 help Support running as a Xen Dom0 guest. + +config XEN_PV_MSR_SAFE + bool "Always use safe MSR accesses in PV guests" + default y + depends on XEN_PV + help + Use safe (not faulting) MSR access functions even if the MSR access + should not fault anyway. + The default can be changed by using the "xen_msr_safe" boot parameter. diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index 8c2acccebfe1..0ad3d4bf52b3 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -108,6 +108,16 @@ struct tls_descs { */ static DEFINE_PER_CPU(struct tls_descs, shadow_tls_desc); +static __read_mostly bool xen_msr_safe = IS_ENABLED(CONFIG_XEN_PV_MSR_SAFE); + +static int __init parse_xen_msr_safe(char *str) +{ + if (str) + return strtobool(str, &xen_msr_safe); + return -EINVAL; +} +early_param("xen_msr_safe", parse_xen_msr_safe); + static void __init xen_pv_init_platform(void) { /* PV guests can't operate virtio devices without grants. */ @@ -1010,22 +1020,16 @@ static int xen_write_msr_safe(unsigned int msr, unsigned int low, static u64 xen_read_msr(unsigned int msr) { - /* - * This will silently swallow a #GP from RDMSR. It may be worth - * changing that. - */ int err; - return xen_read_msr_safe(msr, &err); + return xen_do_read_msr(msr, xen_msr_safe ? &err : NULL); } static void xen_write_msr(unsigned int msr, unsigned low, unsigned high) { - /* - * This will silently swallow a #GP from WRMSR. It may be worth - * changing that. - */ - xen_write_msr_safe(msr, low, high); + int err; + + xen_do_write_msr(msr, low, high, xen_msr_safe ? &err : NULL); } /* This is called once we have the cpu_possible_mask */ |